That was common here in the Midwest. Most common is baseboard style registers, sidewall registers are less common but I've seen them too, sometimes the house will have a combo of both. One time I was in a house in KC that had registers in the upper sidewall, and the ductwork was still in the basement, both levels were like this. There was a main trunk that ran to the attic and then the branches would drop down the wall to each room for upstairs. This was done in the 1950s which would've made it a rather odd setup for the time. Worked great for A/C though, and it sure does get hot in KC.
