Dictionary.net

The centre of the population of the United States at the time of the census of 1790, lay some twenty-three miles to the east of Baltimore. In 1800, it was about the same distance west of Baltimore; in 1810, about forty miles west-northwest of Washington; in 1820, sixteen miles north of Woodstock, Va.; in 1830, nineteen miles west-southwest of Moorefield, W. Va.; in 1840, sixteen miles south of Clarksburg, W. Va.; in 1850, twenty-three miles southeast of Parkersburg, W. Va.; in 1860, twenty miles south of Chillicothe, O.; in 1870, forty-eight miles east by north of Cincinnati; in 1880, in Kentucky, eight miles west by south of Cincinnati; in 1890, in Southern Indiana.