Slab City, also called The Slabs, is an unincorporated, off-the-grid alternative lifestyle community consisting largely of snowbirds in the Salton Trough area of the Sonoran Desert, in Imperial County, California. It took its name from concrete slabs that remained after the World War II Marine Corps Camp Dunlap training camp was torn down. Slab City is known for attracting people who want to live outside mainstream society.

Prior to the United States' official entry into World War II, the United States Marine Corps planned a training ground for field and anti-aircraft artillery units in an area accessible by aircraft taking off from carriers near San Diego. To create the training base, 631 acres (255 ha) were obtained. The government announced that the base was to be named after Marine Corps Brigadier General Robert Henry Dunlap. After construction of Camp Dunlap was completed, it was commissioned on October 15, 1942. The camp had fully functioning buildings, water, roads, and sewage collections. The base was used for three years during the war. By 1949, military operations at Camp Dunlap had been greatly reduced, but a skeleton crew continued on until the base was dismantled. By 1956, all buildings had been dismantled, but the concrete slabs remained.

The area that is now Slab City was the artillery training range for the Camp. It was first settled by a few veterans who had worked at the Marine base, followed later by drifters – then recreational vehicle owners, searching for free camping spots outside Palm Springs. Current residents refer to themselves as Slabbies while tourists are called Normies.

As of October 6, 1961, a quitclaim deed conveying the land to the State of California was issued by the Department of Defense as it was determined the land was no longer required. The deed did not contain any restrictions, recapture clauses, or restoration provisions. All of the former Camp Dunlap buildings had been removed. The remaining slabs were not proposed for removal. Later, legislation required that revenue generated from this property would go to the California State Teachers' Retirement System.

Slab City's popularity surged after an article was printed in Trailer Life and RV Magazine around 1984. A 1988 San Diego Reader reports there were no more than 600–700 RVs around 1983, and one resident estimated there were about 2000 trailers when he was interviewed in March, 1988.

Leonard Knight, an early settler who created the Salvation Mountain art installation, was featured in Sean Penn's Into the Wild, released in 2007. An obituary of Knight stated that he "spent almost 30 years building the colorful mountain ... Built out of adobe and donated paint, Knight worked on the mountain all day, every day. He even slept at the mountain's base in the back of a pick-up truck, with no electricity or running water".

An article in Smithsonian magazine in October 2018 referred to the community as a "Squatters’ Paradise" which locals consider to be "one of America's last free places." The article said of the population: "There are clearly people there who don’t want to be found, so there’s something about disappearing, and the desert offers that kind of opportunity."

Slab City is located on roughly 640 acres (260 hectares; 2.6 square kilometres) of public land, near the east shore of the Salton Sea. It is 100 miles (160 kilometers) northeast of San Diego, 169 mi (272 km) southeast of Los Angeles and about 50 mi (80 km) from Mexico. To the east of Slab City is Coachella Canal, which is fenced, but the fence gets cut open periodically, especially at Slab City, according to the Coachella Valley Water District.