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Four of Portland’s bridges could soon officially be declared historic.

The State Advisory Committee on Historic Preservation has nominated four bridges along the Willamette River 鈥� the Hawthorne, the Burnside, the Morrison and the Broadway 鈥� for listing on the National Register of Historic Places.

The bridges would join the Vista Avenue Viaduct (better known as the Vista Bridge) and the Portland-Vancouver Highway Bridge (the northbound section of the Interstate Bridge) as the only bridges in the metro area listed on the register.

鈥淧ortlanders love their bridges, but I’m not sure they understand the significance of them,鈥� said George Kramer, who was hired by Multnomah County to write each bridge’s written nomination for the committee. 鈥淲ithout them, Portland as it is today would not exist.鈥�

John Goodenberger, the committee chairman, said a nomination is 鈥渟ort of like a college application,鈥� and must give a detailed look into the structure’s historical significance. He said the four bridges were chosen for their roles in expanding the city and the architectural innovations involved.

鈥淵ou have a huge variety of bridge types in terms of style and construction,鈥� Goodenberger said. 鈥淚t’s a 鈥榳ho’s who’ of important designers.鈥�

In the early 20th century, Portland was a hub of innovative bridge technology. With the city’s port growing, engineers had to design bridges that gave enough space for ships to travel safely below.

鈥淥nce it became connected, Portland became a laboratory for bridge design,鈥� Kramer said. 鈥淪hip captains couldn’t get around the swing-stand bridges, so new methods had to be used.鈥�

One of these methods was the vertical lift, which is part of the design of the Hawthorne Bridge 鈥� the oldest bridge across the Willamette and the oldest operating vertical-lift bridge in the nation. Completed in 1910, the bridge was designed by John Alexander Low Waddell, who is generally credited with building the first vertical-lift bridge in the U.S.

Noted bridge engineer Ralph Modjeski, who played a major part in the design of the Manhattan Bridge and the San Francisco-Oakland Bay Bridge, designed the Broadway Bridge, which was completed in 1917. It’s the largest Rall-type bascule (a reference to its unique drawbridge system) bridge in the world.

The Burnside Bridge is one of the heaviest bascule bridges ever built, with each 鈥渓eaf鈥� weighing 5 million pounds. It was completed in 1926 and later modified by Gustav Lindenthal, who designed the Hell Gate Bridge in New York.

The Morrison Bridge, the youngest of the four up for listing, is a reflection of post-World War II bridge technology and engineering in the 1950s. It was designed by Sverdrup & Parcel, which specialized in aviation engineering 鈥� hence the airport-like look of its control towers.

鈥淭hese bridges represent the work of some of the best bridge designers and innovative bridge technology,鈥� Kramer said.

After the National Register of Historic Places returns the written nominations with recommendations, the state committee will resubmit the nominations and wait for approval.

Chrissy Curran, associate deputy state historic preservation officer, believes odds are good that the nominations will be accepted.

鈥淭hey’re intact, and they look like they were just built, which we call integrity,鈥� she said. 鈥淭o be able to drive over the 1910 Hawthorne Bridge, just like it was over 100 years ago, is amazing.鈥�

Curran added that if the four bridges were recognized as historic places, the committee may move forward in nominating other Portland bridges, such as the Ross Island Bridge.