We’re part of the Orthodox Church in America, which started out as part of the Russian Orthodox Church in the original Alaskan mission in the 1790s.
The early American Church throughout the 1800s moved down the Pacific coast and across the country to cities like Chicago and New York and laid a foundation for hundreds of Orthodox Churches in immigrant heavy portions of the country such as the mining towns of Pennsylvania.
In 1917, the Russian Orthodox Church began suffering under the Bolsheviks and support to the American mission was cut off and we had to take care of our own needs. In 1970, the Russian Orthodox Church recognized the Orthodox Church in America is Autocephalous (self-governing) and since then, we have simply been “the American Orthodox Church”.
See more about the History of the Orthodox Church in America