The program actually lasted 8 years longer than the real Korean War did. The character played by Wayne Rogers was 'spun-off' into a program called 'Trapper John, M.D. (1979)' and mentioned his time at the 4077th M*A*S*H unit on several episodes. The actor playing Trapper John in that series, however, was Pernell Roberts (star of the series, 'Bonanza (1959)'), not Wayne Rogers.
It lasted seven years! M*A*S*H produced two more 'spin-offs' titled, 'AfterMASH' and 'W*A*L*T*E*R'. AfterMASH started the very next season after M*A*S*H ended.
In it, Potter, Klinger, and Father Mulcahy work at a hospital in Missouri. It lasted barely over one year. W*A*L*T*E*R only made it to the pilot stage of production. The pilot was broadcast but the show was not picked up by any network. In that pilot, Walter 'Radar' O'Reilly ends out a cop in St. Louis, Missouri.