Section 4 of the 1790 Pennsylvania State Constitution required that “within 3 years after the 1st meeting of the general assembly, and within every subsequent term of 7 years, an enumeration of taxable inhabitants shall be made in such a manner as directed by law.”
The object of this enumeration was to enable the Legislature to properly apportion the county’s senators and representatives. Taxable inhabitants are generally defined as all males over the age of 21 or females who owned their own property (before 1848, only widowed or single woman could own property in their own name). The 1st enumeration law passed in 1779. In 1800 the law included the enumeration of slaves; an 1821 law included the deaf and dumb; an 1836 law required the enumeration of the blind.
Most census years only contain the township, name and occupation of the taxable. Ages, race and sex may be indicated for slaves and inhabitants who were identified as deaf, dumb or blind.
 Statutes at Large of Pennsylvania: act of March 29, 1779 (9 St.L.328, 832)
 Statutes at Large of Pennsylvania: act of March 7, 1800 (16 St.L.434, 2119)