Question

In 1830 the initial grid was laid out for the town of Chicago, Illinois, and by 1833 there were 200 houses. The population continued to expand and the city was mostly built of wood-framed buildings until the Great Fire of 1871 gutted Chicago's core. There were 300,000 people living in Chicago at the time of the fire.

The rebuilding of Chicago drove a boom and the population exploded to two million by 1900. This growth created pressure for a taller, denser city. What two inventions in 1850 and 1867 allowed for this upward growth?

Answer

The invention of the cast-iron building frame in 1850 and the hydraulic elevator in 1857 supported the development of taller buildings.