West Virginia's interstate highway system originally consisted of six separate federal expressways totaling 515 miles and constructed over 31 years. Begun in 1957, the network was completed in 1988 at a cost of nearly $2.8 billion. It was expanded in August 1991 to include Interstate 68 from a junction with Interstate 79 near Morgantown eastward through Preston County, a total of 32.2 miles to the Maryland border, and from there on to I-70 at Hancock. This seventh interstate was formerly designated Corridor E (U.S. 48), which had been completed in 1976 as part of the Appalachian Development Highway system.

The longest interstate highway in West Virginia is I-77, which enters the state from Virginia via a tunnel under East River Mountain near Bluefield and travels north 187.21 miles to exit via a bridge across the Ohio River north of Parkersburg. It was also the most expensive to build, costing more than $1 billion, and took the longest time to complete. Interstate 77 includes the 88-mile West Virginia Turnpike, built prior to passage of the federal Interstate Highway Act of 1956. The turnpike was constructed in 1952-54 at a cost of $133 million and was a mostly two-lane limited-access highway from Princeton to Charleston for 20 years before a special act of Congress authorized the state Department of Highways to upgrade it as a portion of I-77 at a cost of $618.6 million. The upgrading of the turnpike was completed in 1987.

The second-longest interstate is I-64, which enters the state at the Kentucky border east of Huntington, passing through Wayne, Cabell, Putnam, and Kanawha counties, where it joins I-77 south to a point near Beckley and then resumes its separate easterly route through Raleigh, Summers, and Greenbrier counties to the Virginia border near White Sulphur Springs. Interstate 64 travels 123 miles as a separate highway, and shares 50 miles with I-77. Even though the first interstate construction contract in the state was awarded on I-64 in 1957 for a $131,900 bridge across a secondary road in Cabell County near the Putnam County border at Culloden, I-64 was the last interstate completed. The final 35.82 miles of I-64, between Sam Black Church in Greenbrier County and the West Virginia Turnpike (I-77), were opened to traffic on July 15, 1988.

This final segment of I-64 contains a bridge that rivals the state's famed New River Gorge Bridge on U.S. 19 near Fayetteville. The Glade Creek bridge, east of Beckley, towers approximately 700 feet above a gorge even more rugged and inaccessible than that of New River, a 2,179-foot span which cost nearly $29 million to build. With piers and abutments founded on 36-inch diameter caissons into solid, unweathered rock, the bridge required 1,347,417 pounds of structural steel. Continued traffic growth in the area between Charleston and Huntington brought about a number of six-lane widening projects on the other end of I-64.

Interstate 79 begins at its junction with I-77 two miles north of Charleston and continues northward to the Pennsylvania border north of Morgantown. The 160.52-mile expressway through Kanawha, Clay, Braxton, Gilmer, Lewis, Harrison, Marion, and Monongalia counties cost $447.9 million to build and was a late addition to the interstate system. In October 1961, Federal Highway Administrator Rex Whitten signed a memo authorizing the extension of I-79 into West Virginia from what had previously been exclusively a Pennsylvania highway. The entire 310-mile highway now stretches from Charleston to Erie, Pennsylvania, and connects with I-68 just south of Morgantown. Traffic volumes generated by Clarksburg-area development such as the FBI center resulted in a number of projects to widen I-79 to six or eight lanes.

One of the state's most heavily traveled interstates is the 26-mile segment of I-81 that crosses the Eastern Panhandle from Virginia to Maryland. It is a small portion of a 900-mile expressway from Knoxville to the Canadian border north of Watertown, New York. Crossing the moderate terrain of Berkeley County, the West Virginia section of I-81 cost less than $1 million per mile to build, the cheapest of the state's interstates.

In the Northern Panhandle 14.45 miles of Interstate 70 cross through Ohio County from Ohio to Pennsylvania. It includes a tunnel just east of the Ohio River in downtown Wheeling and is part of a 2,000-mile national superhighway that begins in Baltimore and ends near Salina, Utah. Interstate 470 is a 3.95-mile bypass of downtown Wheeling that begins in nearby Ohio and terminates with I-70 east of Wheeling.

Interstate exits or interchanges are numbered in miles from the point at which the route enters the state, west to east on even-numbered interstates and south to north on those with odd numbers. Thus, Exit 58B for the Civic Center in Charleston is approximately 58 miles from the Kentucky border west of Huntington, while I-77 Exit 173 for Camden Avenue in Parkersburg is approximately 173 miles from the Virginia border near Bluefield.

The state's share of the cost of the interstate system was 10 percent, and much of the money came from a trio of constitutional amendments ratified by voters that authorized the issuance of general obligation bonds to finance highway construction. The Better Roads Amendment of 1964, which was voted on in the 1964 general election, was approved by a vote of 455,294 to 116,438 and provided $200 million for the "building and construction of state roads and highways." Four years later, voters ratified the Roads Development Amendment of 1968 by a vote of 366,958 to 159,971, providing another $350 million. In a special election in November 1973, voters again approved a Better Highways Amendment for $500 million in highway funding, by a vote of 172,187 to 61,308.

The improvement and maintenance of the 549-mile interstate system represents an ongoing commitment by state highway officials. Projects are undertaken as traffic demands and funds allow.