Thanks for all the nice compliments.
The terrain base is a DEM, then for my area of interest I hand drew a detailed elevation model using an orthophoto as a guide. There's an additional displacement map to raise the roadbed and give the pavement the required slope out from center, plus one for potholes, then a further masked layer of displacement for cracked pavement.
I modeled all the man-made objects including Shirley's Diner, the Union 76 station, the Lincoln Lodge, (how's that for a patriotic group of names?) grain elevators, roadsigns, utility poles, houses, and even a couple of house trailers in the distance. I posted my corn model in another thread a while ago. Most if not all of the textures I've made too.