Steilacoom was founded twice in 1851. Two land claims were filed in this best place on the South Sound, as Captain Lafayette Balch established Port Steilacoom with a 315-acre donation claim on January 10, 1851, and the lawyer John Chapman filed his own land clam for the adjacent 312 acres in October of the same year and named it Steilacoom City. The two were merged by act of the Territorial Legislature on April 22 of 1854, but are still divided by Union Avenue, where the angle of the streets changes.
The town has some of the oldest intact residences in the State, with a few built with box construction, a style largely replaced by balloon framing by 1880. Many historic houses have their names and construction dates on a small sign located near the door.