[2] In the U.S., the back-up beeper was first manufactured by Ed Peterson who sold the system to Boise engineering firm Morrison Knudsen in 1967.
As of 1999, the company marketed the Bac-A-Larm and sold about one million of the backup alarms annually, more than other suppliers.
[7][better source needed] In some countries, back-up warning systems using blasts of white noise have become more common.
[8] Back-up beepers or an observer are required by OSHA for earth-moving vehicles with an obstructed view to the rear and no one on the ground to help guide the driver.
[9] OSHA regulation 29 CFR Part 1926.601(b)(4) requires "a reverse signal alarm audible above surrounding noise level", but only when the motor vehicle has "an obstructed view to the rear".