Question: In what year did the Highway that connects the major metropolitan areas of St. Louis, Louisville and Lexington in Kentucky, Charleston, West Virginia, and Richmond, Virginia open?

Related documents: [0]  [DOC] Grayson is a home rule-class city in and the county seat of Carter County, Kentucky, United States, in the state's northeastern region. The population was 4,217 at the 2010 census. Along with Carter County, the city is closely associated with the nearby Huntington-Ashland, WV-KY-OH Metropolitan Statistical Area being just 9 miles west of the M.S.A's western boundary. The city has grown in size substantially since the opening of Interstate 64 in 1975 through Carter County. Immediately afterwards, Grayson experienced several years of commercial sector growth to serve the Interstate 64 traffic. Since 1990, the city has also seen significant growth in the residential sector with the Interstate making for a faster trip to and from Ashland. Beginning in 1995, AA Highway terminates in Grayson making the city a gateway to the Huntington-Ashland urban area. [END] 
[1]  [DOC] Interstate 64 (I-64) is an Interstate Highway in the Eastern United States. Its western terminus is at I-70, U.S. Route 40 (US 40), and US 61 in Wentzville, Missouri. Its eastern terminus is at an interchange with I-264 and I-664 at Bowers Hill in Chesapeake, Virginia. I-64 connects the major metropolitan areas of St. Louis, Louisville and Lexington in Kentucky, Charleston, West Virginia, and Richmond, Virginia. [END]  
Answer: 1975
1975