Launch Pad 37A is a bit of a misnomer. Originally planned and built in 1962 (along with LC-34) pad 37A was never used.
Looking at the aerial image it is clearly apparent that the design of LC-37 was to include 2 active pads. The blockhouse was constructed at the apex of the triangle between pads and blockhouse, equidistant from both pads. The orbiting access road is symmetrical around both pads, yet there were never any flights from 37A.
LC-37B however is a very different matter. It saw 7 Saturn I launches between January 29th 1964 and January 22 1968. In 1971 it was deactivated with it structures removed in 1972 when it lay dormant until 2002 when it was repurposed for the new Delta IV missions.
For more information about the current status of the launch complex check the entry for SLC-37B.