The Forest Citys had been a strong team during their amateur / semi-professional years, but before the 1871 season began, their star pitcher Al Spalding had signed with the Boston Red Stockings.
The rest of their star players, including Cap Anson and Bob Addy, signed with other teams for 1872, and the Rockford Forest Citys disbanded.
Contemporary and historical accounts describe the park during the 1866-1871 period as woefully inadequate for organized baseball, with trees blocking much of foul ground, and third base being uphill from the rest of the diamond.
By the 1890s the property was called Fair Grounds Park and was an occasional home field for Rockford's minor league clubs.
The Winnebago County Fair, after some 50 years at this location, temporarily folded in 1903 and the fairgrounds were sold to the city of Rockford.