Auxiliary routes are generally classified as spur routes, which connect to the parent route at one end, bypasses, which connect to the parent route at both ends, or beltways, which form a complete circle intersecting the parent route at two locations. There are 323 auxiliary Interstates in the United States. There are some routes which connect to the parent route at one end, but connect to another route at the other end; some states treat these as spurs while others treat them as bypasses. Similar to the mainline Interstate Highways, these highways also meet all Interstate Highway standards (with rare exceptions), and they receive the same percentage of federal funding (90%).