The building above is the last of three weigh-lock buildings to be built on this site. The first was built in 1828, the second in 1834 and this final building in 1850.
The building was used to weigh canal boats as they passed, charging them according to the weight of their cargo. After a boat was drawn into the lock beneath the overhang, the water gates were closed at each end, the water was drained out, and the boat settled onto a massive cradle suspended from the balance beam overhead. The registered weight of the boat was subtracted from the measured weight to determine the weight of the cargo.
Canal tolls were abolished in 1883. In 1905 the scales were removed from the building and the upper floor was extended over the lock to provide more drafting room for the state's new "Good Roads" program.
In the 1950's the state planned to route the new Interstate 81 through both the Weighlock Building and City Hall. Community leaders successfully fought this plan and the Weighlock Building was converted to the Erie Canal Museum in 1962.