To help answer your question. My ancestors are from
Sullivan County Tn.
Sullivan Co. Tn (then still NC) was established primarily from
Washington Co. Tn (then NC) including part of
Sullivan Co. including North of
Holston and
Carter Valley settlements was considered part of Va and Tennesseeans were taxed by Old Fincastle,
Montgomery and
Washington Co.'s rather than NC. In 1784 the illfated stste of Franklin was created (records now mostly lost or duplicated in Tn records) and in 1787.
Hawkins Co. was created from the majority of Sulllivans territory (and then some). In 1790 NC ceded its western lands and tennessee became part of the Territory Souht of the
Ohio River, which it remained until 1796 and statehood.
Sullivan Co. remained generally the same from 1787 until now.
The Kentucky-Tennessee boundary, intended to be 36deg 30', was run toofar north in 1779-1780 by
Virginia surveyors. Ky finally accepted this erroneous
Walker Line in early 1820, but significant parts of the boundary remained uncertain until a survey completed in 1859. Some settlers in the disputed strip were uncertain which state they lived in. By contrast, the Kentucky-Tennessee line went west of the Tn river was surveyed in 1819 essentially on 36 deg 30'. It will be easier to understand if you find map guide to the federal census from the 1700 to mid 1800's. Many relations were born in NC and it became part of TN. Or born in TN and it became part of
Ky or Va. Tha maps make it easier to pinpoint a dateline.