USA is the third stage of Pulseman.
The stage starts with a boss, where Waruyama, riding an odd machine on wheels with a particle gun, attempts to kill Pulseman. Pulseman prevails, sending the damaged mech running. Pulseman then travels to the casino mentioned in the mission briefing, where Waruyama has escaped to. After running through the facility, Pulseman confronts and defeated Waruyama on the rooftop, and ends the journey. Unfortunately, Waruyama escapes.
Since Waruyama fights Pulseman in an expansive desert before reaching a casino, it is most likely that Stage 3 takes place in Las Vegas, Nevada.