Crossing the Kennebec River between Fairfield and Benton is complicated by the fact that the quarter-mile-wide river is split into three channels by two islands, Mill Island nearest Fairfield on the west and Bunker Island nearest Benton on the east. Therefore, all crossings of the Kennebec River throughout history have involved three separate bridges.
The first bridges between Fairfield and Benton were wooden toll bridges, completed in 1848. The eastern two bridges were covered spans, but the bridge between Fairfield and Mill Island may have been an uncovered wooden truss. The bridges were tolled until 1873.
From 1887 to 1896 the three bridges were replaced one at a time by metal truss spans. A two-span lenticular pony truss took the place of the westernmost bridge in 1887. The middle bridge between Mill and Bunker Islands appears to have been replaced with a double-span Warren through truss sometime around 1893 or 1894. The easternmost bridge from Benton to Bunker Island lasted until 1896, when it washed out in a spring flood and was also replaced with a metal truss.
In 1934, a third generation of bridges began to rise over the Kennebec between Fairfield and Benton. This time, heavier, two-lane riveted steel trusses were used, including a two-span Warren pony truss between Fairfield and Mill Island, a two-span Parker truss between Mill and Bunker Islands, and a three-span Parker truss between Bunker Island and Benton.
This third bridge trifecta lasted nearly 70 years until 2003, when the fourth and current generation of bridges—this time designed using steel stringers—was constructed to take their place. To straighten out the curves and jogs of the previous routes, the three modern bridges were erected slightly to the south of their predecessors.