Chautauqua County is the westernmost county in the U.S. state of New York. As of the 2010 census, the population was 134,905. Its county seat is Mayville, and its largest city is Jamestown. Its name may be a contraction of a Seneca Indian word meaning "bag tied in the middle". The county was created in 1808 and later organized in 1811.
Long part of the homeland of the Seneca Nation, one of the six nations of the Iroquois Confederacy, Chautauqua County was organized by the state legislature during the development of western New York after the American Revolutionary War. It was officially separated from Genesee County on March 11, 1808. This partition was performed under the same terms that produced Cattaraugus and Niagara counties. The partition was done for political purposes, but the counties were not properly organized for self-government, so they were all administered as part of Niagara County.
On February 9, 1811, Chautauqua was completely organized, and its separate government was launched. This established Chautauqua as a county of 1,100 square miles (2,850 square km) of land. Chautauqua has not been altered since.