WASHINGTON COUNTY HISTORICAL SOCIETY (Washington County, Utah)
WASHINGTON COUNTY BOUNDARY CHANGES
HISTORY
Washington County was formed on March 3, 1852 by an act of the Utah Territorial Legislature. It extended the full width of the territory, 600 miles from the California state boundary at the foot of California's Sierra Nevada Mountains on the west to the crest of New Mexico's Rocky Mountains on the east. The southern boundary was the same as the Utah Territory boundary at 37 degrees north latitude (actually at 36° 59' 56.31532" north latitude). Harmony, one of the only settlements in the area at that time, was appointed as the first county seat.The town of Washington was made the seat of Washington County in 1859 by act of the Territorial Legislature.
In March of 1861, the eastern boundary of the Utah Territory (and hence Washington County) was trimmed to a line lying between the summit of the Rockies and the 109 degrees west longitude (currently determined to be at 109° 2' 42.62019" west longitude).
On March 2, 1861, Congress creating the Nevada Territory which trimmed the western boundary of the Utah Territory (and hence Washington County) to 116 degrees west longitude.
Two additional Utah-Nevada boundary changes further trimmed the western side of Washington County, on July 14, 1862 to to 115 degrees west longitude and on May 5, 1866 to 114 degrees west longitude.
On January 14, 1863, St. George was designated as the county seat and has remained so ever since.
In 1864, the territorial legislature created Kane County out of the eastern portion of Washington County and Toquerville was designated the county seat.
In 1866, the upper Virgin River area was placed in Kane County with Grafton as the Kane County seat. Kanarraville was included in the [Washington?] county at that time, but later returned to Iron County.
In 1867, the Kane County seat was moved to Rockville and then to Toquerville in 1969.
Boundaries changed again in 1883 or 1884, and Toquerville was shifted back into Washington County.
The county achieved its present shape and size in 1892.
REFERENCES
"The Evolution of County Boundaries in Utah"by James B. Allen
Utah Historical Quarterly (UHQ), Volume 23 (1955)
Pages 261-278
"Like Splitting a Man Up His Backbone": The Territorial Dismemberment of Utah, 1850-1896
by William P. MacKinno
Utah Historical Quarterly (UHQ), Spring 2003, Volume 71, Number 2, Pages 100-124
Same article, but with footnotes
"Like Splitting a Man Up His Backbone": The Territorial Dismemberment of Utah, 1850-1896
Lesson Plan by the Utah State Historical Society
Utah Boundary Markings
Class notes by Harold Mitchell
Southern Utah Memories: Utah Size and Shape
by Loren R. Webb, October 20, 2012