The following is a summary of acts which authorized boundary changes for Washington County.
- Acts of 1779, Laws of North Carolina, Chapter 29, created Sullivan County out of parts of Washington County.
- Acts of 1797, Chapter 12, authorized Nathan Shipley of Washington County and John Anderson of Sullivan County to define the boundary line between the counties of Washington and Sullivan starting at the head of Indian Creek to the highest part of the Chimney Top Mountain.
- Acts of 1801, Chapter 54, appointed James Patterson as surveyor and John Parker as marker on the part of Greene County, and Joseph Brown surveyor and George Davis as marker on part of Washington County, to run and mark the line between the counties of Washington and Greene.
- Acts of 1809, First Session, Chapter 27, altered the boundary lines between Washington and Carter counties to place the farm of Elihu Embree in Carter County.
- Private Acts of 1832, Chapter 46, authorized the county courts of Washington and Greene counties to appoint a qualified surveyor for the purpose of running and marking the dividing line between the said counties.
- Acts of 1837-38, Chapter 192, attempted to create Powell County which would have been formed out of parts of Washington, Hawkins, Sullivan and Greene counties had the majority of the people in the affected areas voted to leave their respective counties.
- Acts of 1839-40, Chapter 15, was yet another attempt to form Powell County out of Washington, Sullivan, Hawkins and Greene counties, the formation of which was subject to approval by a majority of the voters in the affected area.
- Acts of 1845-46, Chapter 47, altered the boundary line between Sullivan and Washington Counties so as to place the farms of James Heltern and James Meredith in Sullivan County.
- Acts of 1853-54, Chapter 89, attempted to create Powell County out of portions of Washington, Sullivan, Hawkins and Greene counties, subject to the approval by referendum of the people living in the affected areas.
- Public Acts of 1869-70 (1st Sess.), Chapter 30, again sought to create Powell County out of portions of Washington, Sullivan, Hawkins and Greene counties, all subject to the approval by referendum of the people living in the affected areas.
- Public Acts of 1869-70 (1st Sess.), Chapter 88, changed the boundary line between Washington and Powell County so as to make a straight line from the point where the counties of Washington, Greene and Powell corner in the west to the point where the counties of Washington, Sullivan and Powell corner in the east.
- Public Acts of 1869-70 (2nd Sess.), Chapter 1, altered the boundary lines between Washington and Sullivan Counties so as to place the farms of A.R. Moulton, T.H.Reeves, W.A. Keene, P.C. Morrison, Sarah Vincent, George Vincent, John Hunt, Vanzant Morgan, Eli Keene, Mr. Ballard and J.H. Crouch in Washington County. This act was confirmed by Public Acts of 1871, Chapter 93.
- Public Acts of 1869-70 (2nd Sess.), Chapter 21, altered the boundary line between Carter and Washington counties so as to place the farm of H.P. Phillips in Carter County.
- Public Acts of 1877, Chapter 48, established the boundary line between Washington and Unicoi counties as run by the surveyor of Washington County and reported by him to the county court of said county.
- Public Acts of 1881, Chapter 147, changed the boundary line between Washington and Unicoi counties so as to include the lands of James E. Deakins, A. E. Jackson and James Luttrell in Washington County.
- Public Acts of 1891, Chapter 142, altered the boundary line between Greene and Washington Counties to place the farms of G.M. Gillispie, A.E. Gillispie, Thomas C. Williams and George T. Harris in Washington County.
- Public Acts of 1895, Chapter 176, altered the boundary line between Washington and Greene counties to place the farm of Benjamin Keelber in Washington County.
- Public Acts of 1899, Chapter 171, changed the boundary line between Carter and Washington counties so as to place the entire farm of H.B. Huston in Carter County. This act was repealed by Private Acts of 1915, Chapter 646.
- Private Acts of 1901, Chapter 176, changed the boundary line between the counties of Washington and Greene so as to make the east line of the farm of George H. Hartsell, of the fifteenth civil district of Washington County, the line between the two counties.
- Private Acts of 1941, Chapter 451, transferred the property of J. T. E. Williams from the eighth to the fifteenth civil district of Washington County.
- Private Acts of 1947, Chapter 17, changed the boundary line between the ninth and tenth civil districts of Washington County.
- Public Acts of 1972, Chapter 450, altered the boundary line between Washington and Greene Counties to place the lands of Samuel Waddle in Greene County.
- Public Acts of 1973, Chapter 79, altered the boundary line between Greene and Washington to place the lands of Annald and Beltro Nhomburg in Greene County.
- Public Acts of 1973, Chapter 102, altered the boundary line between Greene and Washington to place the lands of Zule Dolen Hunt and Frances Hite in Washington County.
- Public Acts of 1982, Chapter 855, realigned the boundaries between Greene County and Washington County by detaching from Greene County and attaching to Washington County the land described in this Act, containing 10 acres, more or less, but excepting 1.85 acres which had been sold to C. C. Fox by the owner, Charlie Brown.