We love our interstates.

South Carolina has 892 miles of interstate highways, only 2 percent of the 41,500 miles of roads that snake across the state.

But those interstates handle a quarter of all the state's traffic, and they're getting busier.

Traffic volume on S.C. interstates rose 51 percent during the 1990s, according to the Road Information Project, a national coalition of companies and groups seeking better highways.

During that time nationwide, interstate traffic volume rose 38 percent.

South Carolina's rise in interstate traffic volume ranked seventh-highest in America. Arizona ranked tops, with a 66 percent increase in interstate traffic, followed by Nevada, Mississippi, North Carolina, Utah and Wisconsin.

In 2001, drivers traveled nearly 12 billion miles on South Carolina interstates. In all, the state rang up 45.6 billion miles of travel on its roads.

One reason for more interstate travel is that more South Carolina residents live near an interstate. In fact, 52 percent of the state's residents live within 5 miles of an interstate -- a percentage that didn't change in the 1990s.

The State newspaper's analysis of 2000 census data shows 2.09 million of South Carolina's 4 million residents lived within five miles of an interstate. In 1990, 1.8 million of its 3.5 million residents lived that close to an interstate.

Another reason for more interstate travel is that South Carolina has more interstate to travel on. Since 1991, South Carolina has seen a 9 percent increase in interstate "lane mileage" -- new roads (such as the 1995 opening of Interstate 77 south of Columbia), added lanes on existing interstate, or old roads designated as interstates.

But S.C. interstates aren't nearly as congested as those in the rest of the nation. The Road Information Project says 41 percent of the nation's urban interstate mileage is significantly or severely congested, up from 33 percent in 1996.

In South Carolina, however, 32 percent of its 154 miles of urban interstates were considered congested in 2001. That's up from 30 percent -- a much smaller increase than the national average.