State Highway 3, also abbreviated as SH-3 or OK-3, is a highway maintained by the U.S. state of Oklahoma. Traveling diagonally through Oklahoma, from the Panhandle to the far southeastern corner of the state, SH-3 is the longest state highway in the Oklahoma road system, at a total length of via SH-3E (see below). Route description In the northwest Highway 3 begins at the Colorado state line north of Boise City, Oklahoma. At this terminus, it is concurrent with US-287/US-385. It remains concurrent with the two U.S. Routes until reaching Boise City, where it encounters a traffic circle which contains five other highways. After the circle, US-385 splits off, and SH-3 overlaps US-287, US-56, US-64, and US-412, though US-56 and US-287 both split off within the next . In Guymon, US-64 splits off. At Elmwood, US-270 joins US-412, coming from a concurrency with State Highway 23. SH-3 remains concurrent with US-270 through Watonga. In Seiling, US-183 leaves the concurrency but is quickly replaced by U.S. Highway 281. SH-33 joins the roadbed later. In Watonga, SH-33 and SH-3 split off from US-270 and US-281. Highways 3 and 33 remain concurrent for 28 more miles, until Kingfisher, where SH-3 joins U.S. Highway 81. It will stay concurrent with US-81 for , through the town of Okarche. Three miles after Okarche, SH-3 leaves US-81. This marks the first point that SH-3 has not been part of a concurrency. Through Oklahoma City Beginning at the split from US-81, Highway 3 becomes a major artery in the Oklahoma City highway system, commonly known as the Northwest Expressway because it is a diagonal route and because it serves the northwestern part of the metro area. It skirts the northern limits of El Reno before entering the Oklahoma City limits. The often-congested Northwest Expressway passes through the suburb of Warr Acres and passes close to Lake Hefner. At the intersection with the Lake Hefner Parkway, SH-3 again re-enters a concurrency. The Lake Hefner Parkway ends very shortly after, and SH-3 becomes concurrent with Interstate 44 through the western side of the city. Near Will Rogers World Airport, Highway 3 transfers to I-240 along the southern side of the city. After I-240 ends, SH-3 is transferred onto I-40 (also carrying US-270), which it remains concurrent with for . SH-3E/3W split In Shawnee, SH-3 splits into two highways, SH-3E and SH-3W. SH-3W splits off I-40 onto U.S. Highway 177,