unpaved: 0 km (1998 est.)
United States: total: 6,370,031 km
paved: 5,733,028 km (including 74,091 km of expressways)
unpaved: 637,003 km (1997)
Uruguay: total: 8,983 km
paved: 8,085 km
unpaved: 898 km (1999)
Uzbekistan: total: 81,600 km
paved: 71,237 km (these roads are said to be hard-surfaced, and include, in addition to conventionally paved roads, some that are surfaced with gravel or other coarse aggregate, making them trafficable in all weather)
unpaved: 10,363 km (these roads are made of unstabilized earth and are difficult to negotiate in wet weather) (1996)