Josephine County is located in southwest Oregon and was created by the Territorial Legislature on Jan. 22, 1856 from the western half of Jackson County. It was the 19th, and last, county created before statehood. Josephine County was named for Josephine Rollins, the first white woman to settle in southern Oregon.

The county is bordered on the south by California, on the north by Douglas County, on the west by Curry County at the Coast Range summit, and on the east by Jackson County. Josephine County is predominantly mountainous, but has two major valleys cut by the Rogue and Illinois Rivers.

Sailor Diggings was named the first county seat of Josephine County in 1856. By the next year, the population center shifted north to the Illinois Valley and to Kerbyville, a town founded earlier that year by James Kerby. Kerbyville was chosen by the electorate as the new county seat in 1857. In 1858 the Territorial Legislature changed its name to Napoleon, but Kerbyville, and later, Kerby, remained the favored usage in the county. In 1886 the county seat was relocated to Grants Pass, a new town built along the recently completed railroad. 

The first county courthouse was a log cabin at Sailor Diggings, which was later known as Waldo. The building was purchased for $100 from James Hendershott in 1856. In 1858 when Kerbyville became the new county seat, the commissioners ordered the sheriff to sell the courthouse at Sailor Diggings. Between 1858 and 1886 court records were kept in various offices and buildings rented by the county in Kerbyville. In 1886 the county seat was relocated to Grants Pass where courthouses were built in 1887 and 1917. 

County officers were elected in June, 1856, and included three county commissioners, sheriff, auditor, treasurer, probate judge, and coroner. The U.S. district court held its first session at Sailor Diggings in 1856. Josephine County government currently consists of three commissioners, district attorney, assessor, clerk, sheriff, surveyor, treasurer, and legal counsel. 

Most commercial activity during the territorial period centered on gold mining and the supply of provisions to miners. Miners had been active in the Rogue and Illinois Valleys since 1851. By the late 1850s gold mining was beginning to decline and population dwindled as well. In 1859, gold was discovered along the Fraser River in British Columbia and an exodus from Josephine County occurred. 

Although several Indian tribes lived in the area from which Josephine County was created, most of their members had been moved to reservations by 1856. In late 1856 all Indians in southwest Oregon, with the exception of a few tiny bands, were moved to the Siletz Reservation in Polk County. 

Josephine County was also the home to a large Chinese population. Most came to the area to work gold claims purchased from whites no longer interested in working them. Even though they could not own land, they had to pay a tax to mine gold, and were relegated to inferior claims. 

The population in Josephine County has steadily increased except in the 1910s when there was a 20% decrease. In 2016 the population of 84,675 represented a 2.4% increase from 2010. The principal industries are lumber, tourism, and agriculture.