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 615 miles (990 km) via SH-3E (see below).

SH 3 begins at the Colorado state line 19 mi (31 km) north of Boise City, Oklahoma.

Routes until reaching Boise City, where it encounters a traffic circle which contains five other highways.

Beginning at the split from US-81, SH-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.

The Lake Hefner Parkway ends very shortly after, and SH-3 becomes concurrent with I-44 through the western side of the city.

Near Will Rogers World Airport, SH-3 transfers to I-240 along the southern side of the city.

SH-3 then becomes part of the Richardson Loop, a freeway around the west and south sides of Ada.

The highway then becomes two-lane once again and heads southeast to the town of Coalgate, where begins an 18-mile (29 km) concurrency with US-75, lasting through Atoka.

On 7 January 1963, the highway was given its own alignment from near Idabel to Arkansas, taking over that of SH-21, which was eliminated at that time.

From the highway's commissioning to 1976, there was only one fork of SH-3 between Shawnee and Ada, which was the path of current SH-3E.

[5] House Concurrent Resolution 1067 labeled the highway as "Governor George Nigh's Northwest Passage."