 The United States acquired the Last Purchase, including what is now Cherry Springs State Park, from the Iroquois in the second Treaty of Fort Stanwix in October 1784.In the years that followed, Native Americans almost entirely left Pennsylvania.Potter County was formed from part of Lycoming County on March 26, 1804, but the difficult terrain and thick old-growth forest prevented the new county from being settled by European-Americans until 1808.