Originally constructed in 1910, the Hawthorne Bridge is the oldest operating vertical lift bridge in the United States. The 1,383-foot long Hawthorne Bridge is one of Portland’s busiest bridges, safely carrying approximately 30,000 vehicles and untold pedestrians and cyclists across the Willamette River. Vertical clearance for river traffic is limited and approximately 200 openings per month are required for this vertical lift bridge. Like other vertical lift bridges, the Hawthorne Bridge uses a system of counterweights and cables to move the lift span straight up and down. The operating system is mostly original, but the electrical power and control systems—which were installed in 1975—were upgraded in 1999. Hawthorne’s counterweights each weigh 450 tons and are supported by the bridge’s two towers, which rise 165 feet above the bridge deck. The Hawthorne Bridge’s main span can be raised 110 feet to allow vessels to pass underneath. On average, an opening of the Hawthorne Bridge is 8 minutes long. Major structural modifications on the truss spans have included: Removal of the original timber deck and sidewalk Installation of open steel grating deck and concrete and aluminum sidewalks. Widening the sidewalks from 6 feet to 10 feet to allow greater room for pedestrians and cyclists. This resulted in the overall deck width extending out to 72 feet. The Hawthorne Bridge was designed by Waddell and Harrington, Consulting Engineers from Kansas City, MO and constructed by the Pennsylvania Steel Co and United Engineering and Construction and Robert Wakefield. It opened to traffic on December 19, 1910.