Here's my best guess on the two you mentioned. If you look at the maps for the 1940 Census for Monroe County on the National Archive web-site, you will find that, unlike today, Prairie Rd. is very short. I think that what they called Aberdeen Road then was today's Prairie Road, as it is the main road to Aberdeen. Also, I found a reference (see below) to the Magnolia Route as a 1000 mile drive from Gulfport to Chicago. I imagine that part of it was the main north south route through the area, probably roughly corresponding to US 45 Alt.