Western U.S. residents make the most of the UFO sightings.

The western U.S. residents make the most of the UFO sightings. The reason for that can be the location of some military contractor's research facilities. The Palmdale research plant is known as the Lockheed Martin Skunk Works division. And AREA 51 is in the western USA. And large desert areas in Nevada and the Rocky Mountains offer a paradise for making test flights. Some UFOs might be airships or some other not-very-common vehicles. 

The term "UFO" (Unidentified Flying Object) or UAP (Unidentified Aerial Phenomenon) means an object that looks strange or behaves strangely. And most of them are classified military test planes. 

Some of the most exotic and powerful aircraft in history made their maiden flight from Palmdale to AREA-51. And the most well-known of them are SR-71, U-2, and B-2. So the most promising places to see UFOs are near Palmdale and AREA-51.

AREA-51 location is not far from California (Wikipedia, Area-51)

"Area 51 is the common name of a highly classified United States Air Force (USAF) facility within the Nevada Test and Training Range. A remote detachment administered by Edwards Air Force Base, the facility is officially called Homey Airport (ICAO: KXTA, FAA LID: XTA) or Groom Lake (after the salt flat next to its airfield). Details of its operations are not made public, but the USAF says that it is an open training range and it is commonly thought to support the development and testing of experimental aircraft and weapons systems. The USAF and CIA acquired the site in 1955, primarily for flight testing the Lockheed U-2 aircraft." (Wikipedia, AREA-51)

The Edwards AFB is well-known for space shuttles land and is the home of the X-series test planes. Some of those test planes used rocket engines in maneuver tests. And some of those test planes are sometimes very extraordinary-looking objects. 

That means. People might see extraordinary-looking or extraordinarily behaving aerial vehicles near military and civil test flight areas more commonly than somewhere where there are no research installations. Space installations like Vandenberg AFB also can cause UFO sightings. Those rockets and missiles that were launched from that base caused UFO sightings. 

The west coast is to the Pacific Ocean. And Midway Atoll or its runway. The fastest aerospace vehicles like the X-43 test plane can launched from their mothership aircraft over the Rocky Mountains. Then that system can accelerate to maximum speed over the Pacific Ocean and make a safe landing at Midway Atoll. 

https://en.wikipedia.org/wiki/Armstrong_Flight_Research_Center

https://www.lockheedmartin.com/en-us/who-we-are/business-areas/aeronautics/skunkworks.html

https://www.space.com/ufo-sightings-western-united-states

https://en.wikipedia.org/wiki/Area_51

https://en.wikipedia.org/wiki/Skunk_Works

https://en.wikipedia.org/wiki/Lockheed_SR-71_Blackbird

https://en.wikipedia.org/wiki/Lockheed_U-2

https://en.wikipedia.org/wiki/NASA_X-43