It was the first Gap Filler site in the nation.

In addition to the main facility, Empire operated two AN/FPS-18 Gap Filler sites:

In addition to the main facility, Richmond operated three AN/FPS-18 Gap Filler sites:

All three Gap Filler sites remain with both the radar towers and support structures intact.

In addition to the main facility, Walker operated several AN/FPS-14 Gap Filler sites:

In addition to the main facility, Houman operated an unmanned Gap Filler site:

In addition to the main facility, Z-129 operated several unmanned Gap Filler sites:

In addition to the main facility, Charleston operated two unmanned Gap Filler sites:

The other two Gap Filler sites have been obliterated and redeveloped.

The three Gap Filler sites have their support buildings still standing, also abandoned.