The county, with vast mountain masses covering nearly half of its area on the eastern side and the balance of its expanse a level and remarkably fertile plain, originally extended from Mariposa County, on the north, to the Los Angeles County line, on the south, and from the summit of the Coast Range Mountains, on the west, to the summit of the Sierra Nevadas on the east.

Created on July 10, 1852 at the same time Siskiyou and Sierra counties were designated, the large area was maintained until 1856, when Fresno County was created from territory taken from Tulare, Mariposa and Merced counties. In 1861 part of the eastern territory was cut off and joined with parts of Fresno, Mariposa and Calaveras in forming Mono County. Kern County, cut from the southern part of Tulare, was originated as Buena Vista County in 1855, but was not officially termed Kern until 1866. All that portion of Tulare lying east of the Sierras, with a portion of Mono, was set apart for Coso County in 1864, the name being changed to Inyo County in 1866. In 1872 the southern boundaries of Tulare and Inyo were changed by placing them on the sixth standard parallel south of Mount Diablo, thus drawing a direct line across the state, which still forms the northern boundary of San Luis Obispo, Kern and San Bernardino counties. In 1874 the Fresno-Tulare line was re-formed, placing the boundary along township and section lines rather than along the mountain ridges as theretofore. In 1875-76 another slight change in the Fresno-Tulare line was made, returning to Fresno five square townships, this boundary continuing to the present time. In 1893 Kings County was created from the western part of Tulare.

Within the confines of Tulare County are now 4,935 square miles, or 3,158,400 acres. Were the state of Connecticut lifted bodily from the Atlantic Seaboard and transported westward, it could be set down in California, but it would not quite succeed in covering Tulare County.

The county has an interesting historical aura which dates back to 1770. The first Americans to visit the valley came after 1800. The settling of the country about Visalia, the creation of the county, the struggles of the early settlers, the wars with the Indians, and the growth and development of the country present an interesting story which can be found in a number of the published histories for the county.