Counties by Formation Date
| County | Legislature Approved | Formed | Rank |
|---|---|---|---|
| Mason | November 5, 1788 | May 1, 1789 | 8 |
| Campbell | December 17, 1794 | May 10, 1795 | 19 |
| Bracken | December 14, 1796 | June 1, 1797 | 24 |
| Pendleton | December 13, 1798 | May 10, 1799 | 28 |
| Gallatin | December 14, 1798 | May 13, 1799 | 30 |
| Boone | December 13, 1798 | June 1, 1799 | 35 |
| Owen | February 6, 1819 | April 1, 1819 | 63 |
| Grant | February 12, 1820 | April 1, 1820 | 67 |
| Trimble | February 9, 1837 | April 1, 1837 | 86 |
| Carroll | February 9, 1838 | March 1, 1838 | 87 |
| Kenton | January 29, 1840 | April 30, 1840 | 90 |
Counties first had to be approved by an Act of the Legislature, which was followed by a date on which the county was actually formed, the technicalities of which we don't completely understand.