My old joke is that St. Louis architects and builders liked to design apartment buildings that looked like houses, so people could go in and out with revealing that they were renters. The houses above and below were built as apartment buildings, but my, they are beautiful!
The rest of Waterman Boulevard has houses and two-family flats, with the fronts doors often hard to see. They are stunning houses, with many of them rented to Washington University students.
There are “traditional” apartment buildings, as well. They are usually six-families.
The three-family flat below is something I would expect to see in Chicago.