In 1870 the U.S. population was 39,818,449 and 25% urban
        In 1910 the population was 91,972,266 and 46% urban

• railroad networks caused businesses to move to big cities
• more people worked in factories and fewer (proportionately) on farms
• immigrants increasingly were city people, not farmers

 Syracuse NY

• instead of businesses and housing being mixed together cities developed central business districts
• land became very valuable in these central business districts and buildings became taller
• skyscraper:
• cast iron began to be used for columns and arches in the early 19th century--borrowing technology from bridgebuilding
• but to really take advantage of this technology you needed a new way of thinking--steel frame construction where the walls hang from the skeleton instead of loadbearing masonry walls
• need--big firms, efficiency, concentration of office space, display--led to taller buildings with load-bearing walls with cast iron interior columns in 1889--eg. 16 story Monadnock building, with exterior brick walls more than 10 feet thick.
• the limits of loadbearing construction was that the walls had to carry the entire weight of the building.  Therefore it was very expensive and used primarily for religion and the vanity of rulers
• Skeleton frame construction developed about 1890 for the skyscrapers of Chicago. First skeleton frame was 1885 for a 9 story building, then 1892 for 21 stories.

 Leiter Building--early steel frame construction
• when a 26 story building was build in Manhattan many said that the maximum height had been attained, but 1912 a 55 story building was built and in 1932 the Empire State Building was 86 stories.  The World Trade Center was 110 stories--more than 1/4 mile.
• what else do you need?  piles driven by a steam hammer for the foundation, reinforced concrete, metal lathes, vertical chases for plumbing, heating, electricity, and telephone
• elevators with safety devices were necessary for buildings more than about 5 stories tall
• architects eg. Louis Sullivan either tried to use the new elements and focus on form or tried to keep to tradition and used classical and medieval decorations.  Development of the new profession of structural engineering, with theories of truss design, etc.
• competition in New York for the tallest and most glamorous building: the story of the Chrysler Building  is a classic.  skyscraper film
  

• factories were sited near railroads
• immigrant workers found housing near the factories
• conditions were often extremely bad
• Mary McDowell, a reformer who worked in the slaughterhouse district of Chicago, said that in the summer the houses were so black with flies that you couldn't tell what color the house had been painted.  She focused paticularly on ending the practice of dumping the city's garbage in open pits in that neighborhood and on cleaning up Bubbly Creek, which was bubbly because the slaughterhouses dumped their waste in it.
  

• electric trolleys made it possible for people to live farther from their work (they were faster than horsedrawn trolleys)
• middle class people moved to the edge of the city, to neighborhoods with people like them.  There is a classic book on this: Streetcar Suburbs: The Process of Growth in Boston, 1870-1900, by Sam Bass Warner.
  
• they wanted someplace healthier (sanitation was still primitive) and less congested to live than the center city
• people still had to walk to the streetcar stop so lots were small (typically 1/10 acre), but single family houses began to replace row houses
• these neighborhoods were much more homogenous--often divided not only by income but also by ethnicity
• amusement parks were sometimes built at the end of the line to increase travel to the end (Coney Island in New York is the most famous example, in Richmond, Virginia, it was Forest Hill)

 Coney Island postcard