Berkshire Opera Company ended in 2009.
American Opera Company was created in 1937.
Canadian Opera Company was created in 1950.
Chicago Opera Company was created in 1940.
Birmingham Opera Company was created in 1987.
Boston Opera Company was created in 1908.
Lancaster Opera Company was created in 1951.
Century Opera Company was created in 1913.
Philadelphia Opera Company was created in 1938.
Beecham Opera Company was created in 1915.
Opera Company of Boston was created in 1958.
Opera Company of Philadelphia was created in 1975.