 For example, NC 90 used to run along modern US 64, which explains the multiple "90s" that branch off US 64 today (NC 9, NC 97 and NC 98).Three-digit numbered roads were less important spurs off the two-digit roads and often served as rural connectors.These were numbered in a scheme opposite of the U.S. and Interstate auxiliary routes; the spur routes received an extra "ones" digit instead of an extra "hundreds" digit.