I was in Georgia some months ago and started seeing school buses parked off in the distance. At first it was only a dozen or so and I assumed there was a school nearby.
Soon we were close enough to see it was hundreds of busses. And then we reached the place and discovered we were driving past Blue Bird. Pretty cool.
At least some of the old bus makers are still in business. Once you know the brand it shouldn't be too hard to find out.