How did it get started?

There have been Anglicans in what was to become the United States since the establishment of the first English colony at Jamestown. Following the American Revolution, some reorganization was necessary for those Anglicans who chose to remain in the new country, as the Church of England is a state church which recognizes the monarch as her secular head. Thus the "Protestant" Episcopal Church of the U.S.A. was born (the word "Protestant has since been dropped from the official title). There were some early struggles, for example when bishops of the Church of England were reluctant to consecrate new American bishops who could not, of course, recognize the reigning monarch as the head of the church. This and other matters were resolved however, and today the Episcopal Church is now "in communion" with the Church of England and with other Anglican churches throughout the world.