Knoxville Iron Company was created in 1868.
Canadian Opera Company was created in 1950.
Chicago Opera Company was created in 1940.
Lancaster Opera Company was created in 1951.
American Opera Company was created in 1937.
Philadelphia Opera Company was created in 1938.
Berkshire Opera Company was created in 1962.
Century Opera Company was created in 1913.
Beecham Opera Company was created in 1915.
Opera Company of Boston was created in 1958.
Manhattan Opera Company was created in 1906.
Early Opera Company was created in 1994.