The US Highways that never were:
By Robert V. Droz. Alignments for US 0, US A1A, US 39, US 47, US 88,
US 100, and US 402. Also, there is a list of the US highway numbers
still not used.
http://www.us-highways.com/us0999.htm
Fictional Freeways:
By Brandon Gorte. Covers Michigan's Upper Peninsula; Minnesota;
Wisconsin; and the Chicago, Illinois area in the United States; and
Northern Ontario in Canada.
http://www.great-lakes-hwys.org/fictionalfreeways.html
Fictional Freeways:
By Swamphen Publishing. Southern United States, primarily Florida.
http://www.swamphen.net/roads/fic/