Utah County roads
Made in TileMill (which I read about on the Routelines about page — thanks to Tod Robbins for telling me about it).
I took the Census Bureau’s shapefiles for Utah County, imported them into TileMill, styled the lines a little, and exported to SVG. Then I imported it into Illustrator, applied a thin pencil brush (it’s not very noticeable, honestly), exported to PNG, pulled it into Photoshop, and added some color and texture. Voila: the roads of Utah County.