In the US Highway system, three-digit numbers are assigned to spurs of one or two-digit routes. US 201, for example, splits from US 1 at Brunswick, Maine, and runs north to Canada. Not all spurs travel in the same direction as their "parents"; some are connected to their parents only by other spurs, or not at all, instead only traveling near their parents, Also, a spur may travel in different cardinal directions than its parent, such as US 522, which is a north–south route, unlike its parent US 22, which is east–west. As originally assigned, the first digit of the spurs increased from north to south and east to west along the parent; for example, US 60 had spurs, running from east to west, designated as US 160 in Missouri, US 260 in Oklahoma, US 360 in Texas, and US 460 and US 560 in New Mexico. As with the two-digit routes, three-digit routes have been added, removed, extended and shortened; the "parent-child" relationship is not always present.