Vandenberg
Vandenberg is a US Military Department of Defense space and missile testing base just North of Los Angeles, California
This base is used for unmanned rocket launches into polar orbit.
Pegasus, Taurus, Minotaur, Atlas V,Delta IV and SpaceX's Falcon
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An interesting fact was that before the Challenger Space Shuttle disaster in 1986, $4 billion was spent on the cancelled Space Launch Complex 6 at Vandenberg intended for polar Space Shuttle missions.
Enterprise at Complex 6 for tests in 1985
Complex 4
Complex 4 East and 4 West was used by Atlas and Titan rockets between 1963 and 2005.
SpaceX launches its Falcon 9 Rocket from SPACE LAUNCH COMPLEX 4 EAST since 2013, Vandenburg is ideal for satellites requiring a Polar orbit.
SpaceX also has leased Launch Complex 4 West in February 2015 in order to use that area as a landing pad, currently all the landings have taken place on SpaceX's drone ship, dubbed “Just Read the Instructions” off the Pacific coast.
BFR reusable launch System
There is a chance by 2020 that Vandenberg AFB via the US Space Corps will acquire its own SpaceX BFR launch mount along with a BFR(Now called StarShip) to allow rapid space response, The US military is currently financially supporting SpaceX with the development of its new Raptor rocket engines required for the BFR reusable launch system.
As of 2023 SpaceX have acquired the go ahead for their second launch pad lease for the Space Launch Complex 6 (SLC-6), Only time will tell if this will be for SpaceX's new Starship or Falcon Heavy launches.