In the 1930s, the United States government created the Federal Housing Administration, which in turn created a series of maps which were using a color-coding system to determine which neighborhoods should and should not receive federal housing loans.
În anii 1930, guvernul Statelor Unite a creat Federal Housing Administration, care la rândul său a creat o serie de hărți care foloseau un sistem color de codare pentru a stabili care cartiere ar trebui sau nu să primească credite ipotecare federale.