A great many young men of [Jerseyville] have taken to base ball as fish do to water, and have been at it without any interruption from outsiders for the last three years until last week, when Dr. J.O. Hamilton had a number of them arrested for playing inside the corporation. The base ballists will have their trial to-day before Judge Peter P. Voohrees JW. Merrill prosecutes, and Hon. Robert A. King defends young America.-Missouri Republican, August 30, 1870
The earliest account of baseball in Jersey County that I had before this was from 1875 but this article, which was headlined "War on Base Ball," shows that the game was being played there around 1867. That's not exactly surprising, as it fits with what we know about baseball's spread pattern, but it's useful information.