|The planned Vandenberg launch site.|
Source: Space Flight Now.
But that's not to say that Vandenberg isn't still used for unmanned launches... launching from the Vandenberg AFB is perfect for achieving a polar orbit. Polar orbits are ideal for Earth-observing satellites because they allow you to look at any point on Earth, during daylight, during any given 12 hour period.
|The Enterprise at Vandenberg.|
In contrast, launches from Cape Canaveral never pass over locations above or below 57 degrees latitude. So, the International Space Station, which is accessible from a Cape Canaveral launch, never passes over most of Alaska, or any of Finland, or the North Pole, or Antarctica. But a polar-orbiting satellite would.
By the way, you can track the International Space Station in real time here.
|Polar orbits: preferred by the U.S. Air Force and Santa Claus.|
It's not safe to launch a spacecraft into polar orbit from Cape Canaveral because the rocket will launch north or south, straight up the east coast and over all the cities there, or down the Florida peninsula and over all the cities there.
But, from Vandenberg you can launch due south over the Pacific, without flying over a single inhabited bit of land for hundreds or even thousands of miles.
Source: City Data.
So that's why polar orbits are useful, and why Vandenberg would have been the preferred spot for a polar space shuttle launch. In his biography, astronaut Mike Mullane (a retired Air Force colonel) gives his take on the the Air Force's interest in the Vandenberg space shuttle program and U.S. manned space flight in general. To sum it up, Astronaut Mike thinks the Air Force wasn't too interested in manned space flight at all. As a result, the Air Force did not lobby on behalf of Air Force astronauts or space shuttle funding to the degree it could have. The Air Force's lack of interest affected Mike personally, so he has a lot more to say about it than I just did... but you get the idea.
|The Air Force's classified mini-space shuttle, just after landing.|
Source: Discovery News.
However, that's not to say that the Air Force isn't interested in unmanned space flight. Even though the Vandenberg launch site was never used for the space shuttle, it is playing a role in the missions of the Air Force's classified, unmanned space shuttle, the X-37B.
|The X-37B, just after landing at Vandenberg.|
Source: Daily Mail.
Both of the X-37B's missions to date were launched from Cape Canaveral, but landed at Vandenberg! I wonder if there are plans to launch X-37B missions from Vandenberg any time soon?