Map of US highway 70 and family, and US 412
US 70 is represented by the purple line beginning in Atlantic NC. Its western terminus is currently in Globe AZ; the red line extending west of there to Los Angeles CA is the historic extent of US 70. The blue lines in Tennessee represent US 70N and 70S (between Nashville and Knoxville), and US 70A (near Jackson). West of the TX/NM line, the original US 70 followed the red line to Holbrook AZ. Later it was truncated at Texico and instead followed its current route to Alamogordo, but south from there it followed the red line to El Paso.
US 170 (historic) is the red line from Lynchburg VA to Charlotte NC.
US 270 [I] (historic) is the red line from Sparta to Murfreesboro TN (this was swallowed up by US 70S).
US 270 is the blue line beginning in Pine Bluff AR. Its western terminus is currently in Liberal KS; the red line north and west from there is the historic extent of US 270.
US 370 (historic) is the red line from Amarillo to Bowie TX.
US 470 (historic) is the red line from Albuquerque to Willard NM.
US 412 is also shown on this map (the green line from Columbia TN to Springer NM). Because its number is a major violation of US route numbering conventions, I included it on this map to demonstrate how the highway would fit into the US 70 family, if it were to be assigned a number US x70. (This is just one of several other possibilities that make more sense than 412; I've also included the route on the maps for US 56, US 60, US 62, and US 64).