A transit district or transit authority is a special-purpose district organized as either a corporation chartered by statute, or a government agency, created for the purpose of providing public transportation within a specific region.

In the United States, this is usually within one state, but in rare circumstances may cover two or more states. The term used depends on which part of the country the agency is created in. Typically, western states will create a "transit district" and eastern states create a "transit authority" but the type of agency is generally the same.

A transit district is created to give it the power of the government in dealing with solving problems related to transit issues. This includes the powers of eminent domain to obtain space for rights of way (e.g. for railways or busways), the ability to impose excise, income, property, and/or sales taxes to fund subsidies of operating costs of local transportation, and the ability to operate independently of the cities and counties that the transit district operates within. A transit district may also have its own transit police force, although in some areas the local police provide a special bureau for this purpose.

Antelope Valley is located in northern Los Angeles County, California and the southeast portion of Kern County, California, and constitutes the western tip of the Mojave Desert. It is situated between the Tehachapi and the San Gabriel Mountains.

The valley was named for the pronghorns that are said to have roamed there until being eliminated by hunters and bad weather in the 1880s. The principal cities in the Antelope Valley are Palmdale and Lancaster.

Shaped like a sideways letter "V", the Antelope Valley comprises the western tip of the Mojave Desert, opening up to the Victor Valley and the Great Basin to the east. Lying north of the San Gabriel Mountains and southeast of the Tehachapis, this desert ecosystem spans approximately 2,200 square miles (5,698 km²). Precipitation in the surrounding mountain ranges contributes to groundwater recharge.