Listen closely and you can faintly hear a 2001 in there.
There's that Thunderbolt (mentioned above) in Rolla one can see from I-44 across from the Missouri Science and Technology residence halls, but that's all I know of their siren system. Rolla's a dirty, cluttered town and I don't much like stopping there if I can avoid it.
Whatever that siren is (and it sounds VERY much like an Allertor), it sounds like it is on its last legs.
EDIT: I've got myself on the prowl for this mystery siren because now I'm curious, seeing that I have to go past Rolla whenever I drive to St. Louis. They hide their sirens well; I found an article saying they have 21 sirens (!). I've managed to find a 2001 so far.
http://maps.google.com/maps?f=q&source= ... ,,0,-10.87
Another 2001:
http://maps.google.com/maps?f=q&source= ... 8,,1,-2.16