The river, which flows throughout the northern half of Beaver County, serves as the namesake of the county as well as several locales in both Beaver and Lawrence County. The river itself was either named for King Beaver of the Lenape tribe that was native to the area, or for the animal itself. Until the partition of Lawrence County from parts of Beaver and Mercer County in 1849, the river was entirely located in Beaver County, with its upstream terminus being at the border between Beaver and Mercer County from 1800-1849.
A letter written by Richard Butler (the namesake of nearby Butler County), dated November 25, 1789, relates the circumstances of Parsons' death:
“I am sorry to inform you that I have every reason to fear that our old friend, General Parsons, is no more. He left this place [Pittsburgh] in company with Captain Heart, (who is sent to explore the communication by way of the Beaver to Cuyahoga and the Lake), on the 5th instant, he had sent a man with his horses from the place where he had encamped the night before, and directed him to tell Lieut. McDowell, who commanded the Block House below the falls of Beaver, that he (General Parsons) would be there to dinner. A snow had fallen in the night which had retarded the progress of the man with the horses. At one place on the Beaver shore he saw where a canoe had landed, and a person got out to warm his feet by walking about, as he saw he had kicked against the trees and his tracks to the canoe again. The man did not get down till evening, but about noon the canoe, broken in pieces, came by the Block House, and some articles known to belong to General Parsons were taken up and others seen to pass. Lieut. McDowell has diligent search made for the body of the General, but made no discovery.”
His body was recovered the next May, then temporarily buried on the banks of the river. But through a series of mishaps the site of the grave was lost. It has never been found.