The Northport Bridge's total length is 1,542 feet (470 m).

The bridge opened to traffic on June 13, 1951, at a cost of $1,751,587.

[2] The bridge was designed by George Stevens of the Washington State Highways, and the main span was built by the Midland Structural Steel Company.

Floods in 1948 undermined the south main pier of the steel structure, causing the design to be changed from a section of earth fill to five additional T-beam concrete approach spans.

Underwater blasting was required to remove the south pier for the altered work, resulting in a 673-foot (205 m) series of concrete approach spans on the south.