Bwyababe2 hasn't done their homework.
OKLAHOMA! was on tour for 10 solid years (1944 to 1954) and should rank up there.
BLOSSOM TIME was a popular road show from 1922 up until the 1950s when it just vanished.
Of the modern shows, EVITA seems to be almost constantly on the road, as does LES MISERABLES.
On the other hand, INTO THE WOODS performed rather weakly on the road and was only on tour about a year and a half..so how did that make your list?
Cast albums are NOT "soundtracks."
Live theatre does not use a "soundtrack." If it did, it wouldn't be live theatre!
I host a weekly one-hour radio program featuring cast album selections as well as songs by cabaret, jazz and theatre artists. The program, FRONT ROW CENTRE is heard Sundays 9 to 10 am and also Saturdays from 8 to 9 am (eastern times) on www.proudfm.com