1. The first American department store was, depending on one's precise definition of a department store, either A. T. Stewart's "Marble Palace" on East Broadway in New York City in 1846, or R. H. Macy's store at 6th Avenue and 14th Street in 1858, or the Zion's Cooperative Mercantile Institution (ZCMI) in Salt Lake City, established in 1868.
2. The first successful passenger elevator, constructed by Elisha Otis, was installed in 1857 in Eder V. Haughwout's five-story china emporium at 488 Broadway in New York City. This allowed buildings with more floors that could be easily accessed by customers.
3. The first rapid transit railway in the U.S. was the elevated train built in New York City starting in 1868. New York's subway opened in 1904. This allowed easy access to downtown locations for potential customers.
4. The first catalog mail order business was begun in 1872 in Chicago by Aaron Montgomery Ward.
5. The first building in the U.S. to use structural steel in its frame—the first "skyscraper"—was the ten-story Home Insurance Building in Chicago, at the corner of La Salle and Adams Streets, built in 1884. This innovation allowed behemoth multi-floor buildings in downtown real estate centers.
6. Escalators, first installed at a few elevated train platforms in New York City in 1900, soon appeared in several New York City department stores, including Macy's, and within a couple of years appeared in Philadelphia and Chicago department stores.