Why was population in western cities increasing ? ?

I believe it was because both blacks and whites were moving west to the cities to find jobs.

hope i helped :)

Austin, Texas, keeps tearing along as the fastest growing big city in the country. According to census figures released today, its population shot up 2.9 percent during the 12 months that end in July of 2014. Among the 50 largest American cities (and to be clear, these figures are for cities proper, not their wider metro areas), the next closest on the list was Denver, which managed 2.4 percent growth. Which is to say, no other major city even came close to Austin's pace of expansion, much as has been the case ever since the recession ended.