Reading Wikapedia one might assume that the U.S. has always used a period "." as the decimal separator. While reviewing and old land grant document issued in Michigan Territory in 1832 by the U.S. government I saw a pre-printed form that shows "the rate of $1,25 per acre." There's no question about meaning because 80 acres cost $100.

So my curiosity has in piqued. In what periods/places was a comma used as a decimal separator in the United States?