Topic summary
Auxiliary Interstate Highway
Extracted from the Wikipedia article List of auxiliary Interstate Highways.
Auxiliary Interstate Highways (also called three-digit Interstate Highways) are a subset of highways within the United States' Interstate Highway System. The 323 auxiliary routes generally fall into three types: spur routes connect to or intersect the parent route at one end, bypasses connect to the parent route at both ends, and beltways form a circle that intersects the parent route at two locations.