The town was on the northern bank of the mouth of the Snake River, in what is now Pasco, Washington. The City of Pasco now consumes the historic townsite and not much can be found of the original settlement.
The townsite of Ainsworth is located along the Snake River just north of Sacajawea State Park, and the confluence of the Snake and Columbia Rivers. There are some gravel and dirt roads along the north side of the park that lead to a very brushy area along the bank of the Snake River. This was the former townsite.
Ainsworth was founded in October of 1879 by Northern Pacific Railway engineers. It was named after Captain J.C. Ainsworth, a prominent official of the Oregon Steam Navigation Company.
When Franklin County was created from Whitman County in 1883, Ainsworth was named county seat. At the time, there were also a number of Chinese laborers who lived in Ainsworth, many of whom worked for the railroad, and the remainder of which operated businesses in town.
Ainsworth averaged between 400 and 500 people, with a maximum of about 1,500 during its heyday. Up to half of the population was Chinese laborers.
In 1884, a railroad bridge across the Columbia River was completed less than a mile upstream from Ainsworth, instead connecting to the new small town of Pasco. This would eventually lead to the end of the town. By 1885, many of the buildings in Ainsworth had either been dismantled or moved to Pasco. The Chinese laborers also moved to the new town, and established their own district, but most of them left when the railroad work was completed and the work let up. In 1885, the State Legislature officially moved the county seat to Pasco.
Over the years, Pasco has increased in size and engulfed the original townsite.
The life of Ainsworth was short with total abandonment occurring in five years. Flooding was a recurring problem here until dams were built in the mid-twentieth century. Little is left, but some old foundations and broken concrete can be seen. A ferry operated here until bridges were constructed, so it is difficult to discern if the remains are from Ainsworth or the ferry. There is the presence of concrete slabs or foundations in the water off the Snake River, just offshore.