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AP USH Unit 6 · Lesson 5 of 14CED Topic 6.5Skill 5.B: Causation~ 50 min

Technological Innovation, 1865-1900

In thirty-five years, Americans went from oil lamps to electric streetlights, from handwritten letters to long-distance telephone calls, from sailing ships and freight wagons to refrigerated rail cars that put Chicago beef on a London table within a week. The second industrial revolution did not arrive as a single invention. It arrived as a system: cheap Bessemer steel, electric power, the chemical industry, the internal combustion engine, the patent-protected research lab. This lesson traces how that system took shape and why it produced the country that would dominate the twentieth century.

Learning Objectives

By the end of this lesson, students will be able to:

  • Identify the major technological breakthroughs of the second industrial revolution between 1865 and 1900, including the Bessemer process, the incandescent light bulb, alternating current, the telephone, the refrigerated rail car, and steel-frame skyscraper construction.
  • Explain how cheap structural steel, electric power, and refrigerated transport reshaped American manufacturing, urban form, and food distribution during the Gilded Age.
  • Account for how the federal patent system and the industrial research laboratory turned individual invention into a repeatable institutional process led by Edison at Menlo Park, Westinghouse at Pittsburgh, and Bell at Boston.
  • Use Skill 5.B (Causation) to trace the chain that connects late-century technology to the dramatic expansion of American industrial production described in KC-6.1.I.B.i.
  • Account for the rivalry between Thomas Edison and Nikola Tesla over direct and alternating current, and explain why Westinghouse and Tesla's alternating-current system became the foundation of the modern American electrical grid.

Key Concepts

The CED frames Topic 6.5 with one Key Concept statement, KC-6.1.I.B.i: businesses drew on technological innovations and greater access to natural resources to dramatically increase the production of goods. The compressed sentence does an enormous amount of work. Between 1865 and 1900 the United States passed Britain to become the world's largest manufacturing economy, and the technologies clustered in this lesson are the reason. Cheap Bessemer steel made transcontinental railroads, the high-pressure boiler, and the steel-frame skyscraper economically possible. Electric power lit American streets, ran American factory floors, and unhitched manufacturing from the river-bank water wheel that had defined the first industrial revolution. The internal combustion engine, the telephone, and the refrigerated rail car each restructured how Americans moved goods, information, and themselves. The Gilded Age was an age of inequality and political turbulence, but it was first an age of technological compounding, and the rest of Period 6 is unintelligible without the technical substrate this lesson examines (Theme WXT).

The story begins with steel. Henry Bessemer, an English inventor, patented in the 1850s a converter that blew air through molten pig iron and burned out the carbon and silicon in roughly twenty minutes, producing high-quality steel that would have taken days to produce by older crucible methods. Andrew Carnegie's Edgar Thomson Works at Braddock, Pennsylvania, opened in 1875 and was designed from the foundation to run on the Bessemer process. Steel that had cost more than one hundred dollars a ton in 1870 cost less than twenty dollars a ton by 1890. Cheap steel rebuilt every railroad in the country with steel rail in place of brittle iron, made the Brooklyn Bridge of 1883 and the Eads Bridge at St. Louis of 1874 possible, and supplied the I-beams that allowed Chicago architects William Le Baron Jenney, Louis Sullivan, and Daniel Burnham to lift commercial buildings ten and twelve and finally twenty stories above the street. The Bessemer process is the single most important technological substrate of Period 6, and the rest of the second industrial revolution sits on top of it (KC-6.1.I.B.i).

Electric power was the second great engine. Thomas Edison opened the Menlo Park laboratory in New Jersey in 1876 and ran it as the first industrial research operation in American history, employing full-time engineers, machinists, glassblowers, and chemists who worked in parallel on the problems that paying customers wanted solved. The phonograph followed in 1877; the practical incandescent light bulb followed in 1879; the central generating station that lit lower Manhattan from Pearl Street followed in 1882; and the motion-picture camera followed in 1891. Edison filed for more than one thousand United States patents over his career, more than any other American of the period. George Westinghouse, working with the Serbian-born engineer Nikola Tesla, pushed a competing alternating-current system that could be stepped up to high voltage for long-distance transmission and stepped back down for safe local use. Edison's direct current required a generating station every mile or two and could not economically light a city the size of Buffalo or Chicago. The War of Currents between the two systems, fought between 1888 and 1892 in courtrooms, trade journals, and a notorious series of public-relations stunts, ended when the Westinghouse and Tesla alternating-current system lit the 1893 World's Columbian Exposition at Chicago and powered the Niagara Falls hydroelectric plant in 1895. The modern American electrical grid is an alternating-current grid because Westinghouse and Tesla won the argument.

"Businesses drew on technological innovations and greater access to natural resources to dramatically increase the production of goods."AP USH CED, KC-6.1.I.B.i (paraphrased)

The third engine was communication. Alexander Graham Bell filed his telephone patent on the morning of February 14, 1876, hours before his rival Elisha Gray filed a competing caveat at the same Patent Office, and by 1900 the Bell System operated more than eight hundred thousand telephones across the country. The telegraph, which had stitched the country together since the 1840s, was joined by the telephone, the typewriter (1873), and the rotary press, each of which industrialized a different part of the white-collar office that the trust and the railroad had begun to require. The patent system was central. The federal Patent Act of 1790 and its 1836 and 1870 reorganizations granted seventeen-year monopolies that protected the commercial value of new ideas, and a generation of American inventors learned to file patents the way generals plan campaigns. Edison's lawyers filed defensive patents around every promising line of work; Bell's lawyers spent more than a decade defending his telephone patent against six hundred separate infringement suits. The patent and the research lab together were the institutional engine that turned technological innovation into a regular feature of American business (KC-6.1.I.B.i).

The fourth engine was transportation and food. The refrigerated rail car, perfected by Gustavus Swift in the late 1870s and rapidly adopted by Philip Armour, allowed Chicago meatpackers to ship dressed beef across the country for the first time. By 1890 a beef carcass slaughtered in Chicago at a Monday morning could be unloaded at a Boston market on Wednesday evening. The result was the disassembly line at the Union Stock Yards, a Chicago industrial achievement that Henry Ford would later study and adapt to automobile production, and a national meat market that drove independent local butchers out of business across the country. The same refrigeration technology, paired with the steam engine, gave the United States ocean exports of beef, pork, and dairy that helped build the country's first significant trade surpluses. The internal combustion engine, developed by Nikolaus Otto in Germany in 1876 and refined by Gottlieb Daimler and Karl Benz in the 1880s, would not produce an American mass automobile until Henry Ford's Model T in 1908. But its first decade, the 1890s, produced enough small American workshop builders (the Duryea brothers in Massachusetts in 1893, Ransom Olds in Michigan in 1897, Henry Ford's first Quadricycle in 1896) to make the gasoline automobile the obvious successor to the horse and the streetcar by the time Period 7 opened.

The visible monument of the second industrial revolution was the city. Chicago's Home Insurance Building of 1885, designed by William Le Baron Jenney, was the first commercial building to use a load-bearing internal steel skeleton in place of masonry walls, and it set off a vertical race that Louis Sullivan and Daniel Burnham turned into the recognizable American skyscraper. Sullivan's Auditorium Building (1889) and Wainwright Building (1891) gave the steel frame an honest exterior expression. Burnham's Flatiron Building (1902) and Daniel Burnham's plan for the 1893 Columbian Exposition projected the new urban form onto a national audience. Electric streetcars and interurban railways replaced horse-drawn streetcars in city after city in the late 1880s, and the Boston subway of 1897 and the New York subway of 1904 followed. The Eastman Kodak roll-film camera of 1888 made photography a middle-class consumer technology, and the sewing machine, perfected by Isaac Singer's company in the 1860s, supplied the ready-made clothing industry that put cheap manufactured suits and dresses into the reach of the working class. The Gilded Age city of 1900, lit by Edison and Westinghouse, framed in Carnegie steel, fed by Swift refrigerated rail cars, photographed by Eastman Kodak cameras, and dressed by Singer sewing machines, was a different built environment than any earlier generation had ever seen (KC-6.1.I.B.i, Theme WXT).

The deeper story is the institutional one. Late-century invention was not the work of lone tinkerers in garrets, even though Americans liked to tell it that way. It was the work of patent-protected corporations that funded full-time research staffs, managed long pipelines of incremental improvements, and treated invention as an ongoing capital expense rather than a stroke of genius. Edison's Menlo Park laboratory was the model; Westinghouse's Pittsburgh research operation, Bell's American Telephone and Telegraph engineering department, General Electric's research laboratory at Schenectady (founded 1900), and DuPont's Wilmington laboratory (founded 1902) were the heirs. The federal patent office, the corporate research budget, and the engineering school at the Massachusetts Institute of Technology, the Stevens Institute, and Cornell together produced the regular pipeline of new technology that the United States economy would draw on for the next century. Period 6 invented the modern industrial research lab as much as it invented the light bulb, and the institutional invention is the one with the longer shadow.

Primary Source Excerpts

The five sources below sample the technological substrate of Period 6 across patents, photographs, and Smithsonian artifacts.

Patent Document National Archives 1876

Alexander Graham Bell, Telephone Patent No. 174,465, March 7, 1876

Image reference: Original four-page typewritten and hand-drafted patent, with claim language and a schematic diagram of the speaking telephone. Public domain. Reproduce digital scans from the National Archives Catalog.

Bell's telephone patent is the canonical case for studying how the patent system shaped Period 6 invention. Filed on the morning of February 14, 1876, the patent beat Elisha Gray's competing caveat to the Patent Office by hours and produced more than six hundred infringement suits over the following two decades. The Bell System defended every one of them, eventually consolidating most of American telephony under a single corporate roof. The document is short, technical, and constitutionally consequential: a useful primer for students on what a federal patent actually does, why the seventeen-year monopoly mattered, and how the Patent Office became one of the central institutions of the second industrial revolution.

Alexander Graham Bell, Improvement in Telegraphy (telephone patent), United States Patent No. 174,465, issued March 7, 1876. National Archives Catalog identifier 302052. View at National Archives →
Patent Document National Archives 1880

Thomas Edison, Electric Lamp Patent No. 223,898, January 27, 1880

Image reference: Edison's incandescent-lamp patent with technical drawings of the carbon-filament bulb and its glass envelope. Public domain. Reproduce digital scans from the National Archives Catalog.

The Edison electric-lamp patent is the foundational document of the American electrical industry. The patent claims a high-resistance carbon filament inside an evacuated glass bulb, the configuration that made the incandescent lamp commercially practical. The Pearl Street generating station that began service in 1882 ran on Edison bulbs lit through a copper distribution network designed around direct current; the choice of direct current would set off the War of Currents with Westinghouse and Tesla a few years later. Read alongside the Bell telephone patent, this document gives students two adjacent windows on the institutional engine that produced the second industrial revolution: the lone-name patent that protects a corporate research laboratory's most valuable single product.

Thomas A. Edison, Electric Lamp, United States Patent No. 223,898, issued January 27, 1880. National Archives Catalog identifier 595477. View at National Archives →
Photograph Library of Congress 1883

Brooklyn Bridge Engineering Photographs, Library of Congress, 1883

Image reference: Period photographs of the Brooklyn Bridge towers, cable-spinning operations, and the completed roadway, taken between 1869 and 1883. Public domain. Reproduce from the Library of Congress digital collection.

The Brooklyn Bridge is the iconic American steel-cable suspension bridge of the late nineteenth century. The towers, designed by John A. Roebling and completed under his son Washington Roebling's direction, rest on caisson foundations sunk through the East River silt. The four main cables, each thirty-six centimeters in diameter, are spun from steel wire produced by the Bessemer and open-hearth furnaces that supplied the rest of the structural steel boom. When the bridge opened on May 24, 1883, it was the longest suspension span in the world, and its photographs circulated as proof that American technical achievement now matched the engineering accomplishments of any European nation. For a Period 6 lesson on technology, the bridge is the most photographable single object the era produced.

Brooklyn Bridge engineering photographs, 1869-1883. Library of Congress digital ID: 2014645363. View at Library of Congress →
Industrial Artifact Library of Congress c. 1880

Bessemer Steel Process Documentation, Library of Congress, c. 1880

Image reference: Period documentation of Bessemer converters in operation at a Pennsylvania steelworks, including illustrations of the converter vessel, the air-blast manifold, and the molten metal pour. Public domain. Reproduce from the Library of Congress digital collection.

The Bessemer converter is the technological pivot on which the entire second industrial revolution turns. The pear-shaped vessel, lined with refractory brick and tilted on trunnions, blows compressed air through molten pig iron and burns out the carbon and silicon in roughly twenty minutes, producing structural-grade steel that older crucible methods produced in days. Pittsburgh's Edgar Thomson Works went on the Bessemer process in 1875, and Carnegie Steel followed at every plant it acquired afterward. By 1890, American Bessemer mills were the largest steel producers in the world, and the cost per ton had fallen by more than eighty percent. Without the Bessemer documentation, students cannot see why steel rail, the steel-frame skyscraper, and the steel-cable bridge all became economically rational at roughly the same moment.

Bessemer steel process documentation, c. 1880. Library of Congress digital ID: 2002698549. View at Library of Congress →
Smithsonian Artifact Smithsonian 1877

Edison Phonograph and Early Recording Technology, Smithsonian Object Record, 1877

Image reference: Smithsonian National Museum of American History object record for an early Edison tinfoil phonograph and related recording equipment. Public domain object photography reproduced from the Smithsonian digital collection.

The phonograph is the unexpected Period 6 invention. Edison filed for it almost casually in late 1877, and his first machine engraved sound vibrations into a cylinder of tinfoil that could be played back through a stylus and a horn. The device announced two things at once: that the Menlo Park laboratory could produce major commercial inventions on demand, and that recorded sound, like the photograph and the telephone, would soon become a routine technology of the modern American household. The Smithsonian object record is the cleanest available teaching artifact for studying the early history of recorded sound, and the most useful single primary source on the surprising breadth of Edison's late-1870s patent output.

Edison tinfoil phonograph and related recording technology, 1877. Smithsonian National Museum of American History, object record nmah_1283677. View at Smithsonian →

Discussion Questions

  1. (Causation) Trace the causal chain from the Bessemer process to the Chicago skyscraper. At which step does the chain depend most heavily on a federal policy choice, and which one?
  2. (Comparison) Compare Edison's direct-current system with the Westinghouse and Tesla alternating-current system. Which features of alternating current proved decisive for long-distance distribution, and what does the outcome of the War of Currents reveal about how technical standards get chosen in a market economy?
  3. (Continuity and Change) Compare American invention before 1860 (Eli Whitney's cotton gin, Samuel Morse's telegraph, Cyrus McCormick's reaper) with American invention between 1865 and 1900. Identify one continuity and one significant shift, and account for the role the patent system and the industrial research laboratory played in producing the shift.
  4. (Causation) The refrigerated rail car turned Chicago meatpackers into national producers and drove independent local butchers out of business. Account for two ways the technology reshaped the geography of the American food economy and one social cost it imposed on producers and consumers outside Chicago.
  5. (Continuity and Change) Consider the late-century cluster of consumer technologies (the telephone, the Eastman Kodak camera, the Singer sewing machine, the electric streetcar). How did each fit into the late-century rise of the urban middle class, and what does that fit suggest about the relationship between industrial technology and social class in Period 6?

Classroom Activities

15 min

Patent Decoding

Project the Bell telephone patent and the Edison electric-lamp patent side by side. Students annotate each in three layers: the legal claim language, the technical drawing, and the commercial product the patent was designed to protect. The class then names two ways the documents reveal how the federal patent system shaped Gilded Age invention.

25 min

War of Currents Trial

Divide the class into three teams: an Edison legal team, a Westinghouse and Tesla legal team, and a jury of investors deciding which system to back for a hypothetical 1891 Buffalo lighting contract. Each team prepares a five-minute case citing transmission distance, safety, and cost. The jury votes; the class compares the result with the actual outcome of the 1893 World's Columbian Exposition contract.

20 min

Skyscraper Stack

Project images of the Home Insurance Building, the Wainwright Building, and the Flatiron Building in chronological order. Students label each building with the technologies that made it possible (Bessemer steel I-beams, electric elevator, electric lighting, riveted steel-frame construction) and trace how each building's height and form depended on a different layer of the second industrial revolution.

20 min

Three Laboratories Compared

Students complete a graphic organizer for three industrial research laboratories: Edison's Menlo Park, Westinghouse's Pittsburgh complex, and Bell's Boston engineering department. Columns cover founding date, signature inventions, full-time staff structure, and the corporate parent the laboratory served. The class closes by writing a one-sentence claim about what the laboratories had in common and what made the institutional model new.

Vocabulary

The cluster of late-nineteenth-century technologies, including cheap steel, electric power, the telephone, the internal combustion engine, and refrigerated transport, that transformed American manufacturing between 1865 and 1900.
The mid-century method of mass-producing structural steel by blowing air through molten pig iron, adopted in the United States at Carnegie's Edgar Thomson Works and central to the late-century steel boom.
Edison's 1879 carbon-filament electric lamp, patented in 1880 and commercialized through the Pearl Street central station that lit lower Manhattan from 1882 forward.
The Westinghouse and Tesla electric-power system that could be stepped up to high voltage for long-distance transmission and stepped back down for safe local use, and that became the standard of the modern American electrical grid.
The late-1880s commercial battle between Edison's direct-current system and the Westinghouse and Tesla alternating-current system, settled in favor of alternating current at the 1893 Chicago World's Columbian Exposition.
Edison's New Jersey research complex, opened in 1876, the first industrial research laboratory in American history and the institutional model for late-century corporate invention.
The federal seventeen-year monopoly granted to inventors under the Patent Acts of 1790, 1836, and 1870, central to the institutional protection of late-century American technology.
Alexander Graham Bell's 1876 invention for transmitting voice across an electric wire, the technology that produced the Bell System and the modern American telecommunications industry.
Edison's 1877 sound-recording machine that engraved vibrations onto a tinfoil cylinder for later playback, the foundation of the recorded-sound industry.
The insulated, ice-cooled freight car, perfected by Gustavus Swift in the 1870s, that allowed Chicago meatpackers to ship dressed beef across the country and built a national meat market.
The Chicago meatpacking innovation, used by Swift and Armour at the Union Stock Yards, that broke beef and pork carcasses into specialized cuts on a moving overhead trolley, a workflow Henry Ford later adapted to the automobile assembly line.
The steel-frame commercial high-rise developed in Chicago in the 1880s by William Le Baron Jenney, Louis Sullivan, and Daniel Burnham, made structurally possible by Bessemer steel and the electric elevator.
The overhead-wire urban tram that replaced the horse-drawn streetcar in American cities in the late 1880s and 1890s, expanding the geographic reach of working-class commuting.
The gasoline-fueled piston engine, developed by Nikolaus Otto in 1876 and refined by Daimler and Benz in the 1880s, that produced the American automobile industry of the early twentieth century.
George Eastman's Rochester company that introduced the roll-film camera in 1888 and made photography a routine middle-class consumer technology by the end of the century.
The corporate research operation, modeled on Edison's Menlo Park, that staffed full-time engineers and scientists to produce a regular pipeline of patent-protected inventions for a parent corporation.
The Serbian-born American engineer whose alternating-current motor and transformer patents, sold to George Westinghouse in 1888, became the foundation of the modern American electrical grid.
The Roebling-designed steel-cable suspension bridge across New York's East River, opened in 1883, the period's most photographed monument to American engineering and the abundant supply of cheap structural steel.

Standards Alignment

Draft alignment — pending educator review. AP USH codes correspond to the official College Board Course and Exam Description (Effective Fall 2023, Version 1). Statements below are paraphrased in the CountryReports voice; refer to the College Board's published CED for verbatim wording.

AP US History CED-ALIGNED

Theme

WXTWork, Exchange, and Technology — the forces that built American systems of trade and production, with attention to how technology, markets, and government policy together drove economic life.

Historical Thinking Skill and Reasoning Process

Skill 5.BAccount for the way one historical development or process is tied to another.
Reasoning 2Causation — account for the connection between the causes and effects of a particular historical development or process.

Learning Objective

LO 6.DAccount for the impact of technological advances on the development of the United States over time.

Key Concept

KC-6.1.I.B.iBusinesses drew on technological innovations and greater access to natural resources to dramatically increase the production of goods.
National Cross-Walks
NCSS Theme 7Production, Distribution, and Consumption — how the second industrial revolution reorganized American manufacturing and the national food economy between 1865 and 1900.
NCSS Theme 8Science, Technology, and Society — the institutional emergence of the patent-protected research laboratory as the late-century engine of American invention.
C3 D2.His.1.9-12Account for how historical context shaped the perspectives of people in different times and places, including the inventors, entrepreneurs, and engineers of the second industrial revolution.
C3 D2.Eco.2.9-12Use marginal benefits and marginal costs to construct an argument about how producers respond to incentives, applied to the rapid late-century adoption of new industrial technologies.
CCSS RH.11-12.2Identify the central ideas of a primary or secondary source and provide a precise summary that relates the ideas to one another, applied to patent documents and engineering photographs.
CCSS RH.11-12.7Combine and assess multiple sources of information, including text, technical drawings, and visual evidence.
Discipline-Specific National Standards
NSH Era 6 · Std 1Account for how the rise of corporations, heavy industry, and mechanized farming transformed the American people between 1865 and 1898.
NSH Era 6 · Std 1BAccount for how the second industrial revolution emerged from a cluster of late-century innovations in steel, electricity, communication, and transportation.
NCGE Std 12The processes, patterns, and functions of human settlement — the late-century shift of the American population into industrial cities supported by new electrical, transit, and structural-steel technologies.
NSES (NRC) Std EScience and technology in society — the social, economic, and political consequences of late-nineteenth-century scientific and engineering breakthroughs.
Other Assessment Frameworks
NAEP US History · G8 / G12Theme 4: The Changes in American Society — the technological reorganization of work, transportation, and urban life during the Gilded Age.
AP World HistoryCross-reference Unit 6 (Consequences of Industrialization) — the United States as one node in a transatlantic late-century technological revolution that included British steel, German chemistry, and French electrical engineering.
AP Human GeographyCross-reference Unit 6 (Cities and Urban Land Use) — the steel-frame skyscraper, the electric streetcar, and the refrigerated rail car as agents of late-century urban form and metropolitan reach.

AP Practice Questions

Multiple Choice Sample ~ 2 min
1Question: The dramatic increase in American industrial production between 1865 and 1900 is best explained as a result of which of the following?
  • (A) The federal abolition of all corporate patents, which allowed inventors to commercialize ideas without legal restriction.
  • (B) The mass adoption of the cotton gin and the McCormick reaper, which industrialized Southern agriculture for the first time.
  • (C) The widespread adoption of new technologies and greater access to natural resources, drawn together inside large patent-protected corporations.
  • (D) The federal nationalization of the railroad, the telephone, and the steel industry under a single Cabinet department.
  • (E) The complete substitution of British and German imported manufactures for domestically produced goods after the Civil War.

Correct: (C). KC-6.1.I.B.i frames the late-century production boom as the joint product of technological innovations (the Bessemer process, the incandescent bulb, alternating current, the telephone, the refrigerated rail car) and greater access to natural resources (Pennsylvania coal and iron, Mesabi Range ore, Pacific timber). The other options invert or fabricate the federal role and the technological story (LO 6.D; Skill 5.B; Theme WXT).

Short Answer Question ~ 12 min · 1 page
2Question: Using your knowledge of United States history from 1865 to 1900, answer all three parts that follow.
  1. Identify ONE specific technological innovation of the second industrial revolution and explain its principal effect on American manufacturing.
  2. Explain ONE specific way the federal patent system or the industrial research laboratory shaped late-century American invention.
  3. Explain ONE specific way the outcome of the War of Currents between Edison and Westinghouse shaped the development of the modern American electrical grid.

Scoring: 1 point for each part. Strong responses to part (a) name a specific innovation such as the Bessemer process (cheap structural steel for railroads, bridges, and skyscrapers), the incandescent light bulb (electric urban lighting and the central generating station), the refrigerated rail car (the national meat market), or the telephone (long-distance commercial communication) (KC-6.1.I.B.i). Part (b) responses might cite the Bell System's defense of the 1876 telephone patent against six hundred infringement suits, Edison's accumulation of more than one thousand United States patents through the Menlo Park laboratory, or the model that Bell, Westinghouse, and General Electric copied from Edison in building corporate research operations. Part (c) responses might cite the role of alternating current in lighting the 1893 Chicago World's Columbian Exposition, the 1895 Niagara Falls hydroelectric plant as the first major long-distance transmission system, or the standardization of alternating current as the foundation of the twentieth-century American grid (LO 6.D; Skill 5.B).

Document-Based Question Stem ~ 60 min · 7 documents
3Prompt: Account for the extent to which technological innovation reshaped American economic and social life between 1865 and 1900. Build your argument with evidence drawn from the seven documents and from your own knowledge of the period.

The full seven-document set for this DBQ lives in the Unit 6 practice exam packet (Document A: Bell telephone patent, 1876; Document B: Edison electric-lamp patent, 1880; Document C: Brooklyn Bridge engineering photographs, 1883; Document D: Bessemer steel process documentation, c. 1880; Document E: Edison phonograph object record, Smithsonian, 1877; Document F: George Westinghouse alternating-current promotional pamphlet, c. 1890; Document G: Eastman Kodak roll-film camera advertisement, 1889).

Scoring framework: 1 point thesis, 1 point contextualization, up to 4 points evidence (at least 3 documents used to support the argument, plus an outside-evidence point), 1 point sourcing (point of view, purpose, situation, audience for at least three documents), 1 point complexity. Maximum 7 points.

Long Essay Question Stem ~ 40 min
4Prompt: Account for the causes and effects of the second industrial revolution in the United States between 1865 and 1900. Build your argument with specific historical evidence drawn from at least three of the developments listed below: cheap Bessemer steel, the incandescent light bulb and the central generating station, the Westinghouse and Tesla alternating-current system, the Bell telephone, the refrigerated rail car, the steel-frame skyscraper, and the federal patent system.

Scoring framework: 1 point thesis, 1 point contextualization, 2 points evidence (at least two pieces of specific historical evidence, one of which directly supports the argument), 1 point analysis using the Causation reasoning process, 1 point complexity. Maximum 6 points.