>>1029749>Westward expansion would have been much, MUCH slower and lots of western America might not actually be, well, America.This is a retarded answer, and it displays a complete lack of even basic knowledge of history.
The bulk of westward expansion occurred in the mid 1800s, while the technological advances that allowed for tall buildings to exist didn't exist until the late 1800s.
>California Gold Rush: 1848-1855>First "Tall" (7-story) office building with an elevator: 1870>First self-supporting steel-framed tower: 10 stories, 1890At this point, 44 of the 48 CONUS states had been admitted to the Union. Utah, Oklahoma, Arizona, and New Mexico were all admitted well before the start of WWI.
Cities as we know them now simply did not exist before the 1900s. The big vertical-construction boom in the US largely occurred between the end of WWI and the start of WWII, whereas the suburban sprawl, highway construction, and elevation of the automobile over streetcars and inter-urban rail are almost exclusively post-WWII phenomenon. Similarly, most of the European and Asian cities that /n/iggers sperg over have been largely built post-WWII. If you want to take OP's suggestion seriously, the timeline split would be sometime ~1938-1945.