The route numbers and locations are coordinated by the American Association of State Highway and Transportation Officials (AASHTO). The only federal involvement in AASHTO is a nonvoting seat for the United States Department of Transportation. Generally, most north-to-south highways are odd-numbered, with the lowest numbers in the east and the highest in the west. Similarly, east-to-west highways are typically even-numbered, with the lowest numbers in the north, and the highest in the south. Some exceptions exist, however, such as spur routes (for instance, US 522 is signed north-to-south, while its parent US 22 is signed east-to-west). Major north–south routes have numbers ending in "1" or "5", while major east–west routes have numbers ending in "0". Three-digit numbered highways are generally spur routes of parent highways (thus U.S. Route 264 [US 264] is a spur off US 64). Some divided routes (such as US 19E and US 19W) exist to provide two alignments for one route. Special routes, which can be labeled as alternate, bypass or business, depending on the intended use, provide a parallel routing to the mainline U.S. Highway.