David Imus worked alone on his map seven days a week for two full years. Nearly 6,000 hours in total. It would be prohibitively expensive just to outsource that much work. But Imus—a 35-year veteran of cartography who’s designed every kind of map for every kind of client—did it all by himself.
▻http://www.slate.com/articles/arts/culturebox/2012/01/the_best_american_wall_map_david_imus_the_essential_geography_of_the_united_s