• The Interstate Highway shield was designed by Richard Oliver of Texas as a black and white shield; the red, white, and blue version was approved by the American Association of State Highway Officials (AASHO) in 1957. It is trademarked.
  • The Federal-Aid Highway Act and Department of Transportation Act passed by Congress in 1966 mandated that all Interstates be four lanes. Previously daily traffic counts determined whether an Interstate would be two or four lanes.1
  • Four state capitals are not served by the Interstate Highway System as of 2006: Juneau, Alaska; Dover, Delaware; Jefferson City, Missouri; and Pierre, South Dakota.
  • It is not true that one mile of every five miles of Interstate highway must be straight enough to allow planes to land on it. This is an urban legend.
  • Previously with one exception (I-65), Interstate 64 overlaps with every two-digit interstate it meets from Wentzville, Missouri to Hampton Roads, Virginia. I-64 overlaps with I-55, I-57, I-71, I-75, I-77, I-81 and I-95. Prior to 2014, I-64 also overlapped with I-70 between St. Louis, Missouri and East St. Louis, Illinois.

Sources:

  1. "Timeline outlines Montana Department of Transportation history." Montana Standard, June 16, 2013.