The Pennsylvania Department of Transportation, abbreviated as PennDOT, owns of the of roadway in the state, making it the fifth-largest state highway system in the United States. The Pennsylvania Turnpike system is long, with the mainline portion stretching from Ohio to Philadelphia and New Jersey. It is overseen by the Pennsylvania Turnpike Commission. Another major east-west route is Interstate 80, which runs primarily in the northern tier of the state from Ohio to New Jersey at the Delaware Water Gap. Interstate 90 travels the relatively short distance between Ohio and New York through Erie County, in the extreme northwestern part of the state.