This table provides a list of formation date of each diocese in the Episcopal Church, as well as an ending date. The Province number as of 2020 is also included to allow for additional reference.

A diocese may be formed a number of ways. Some were formed as dioceses when the Episcopal Church began, typically at the state level. Some were formed after being "Missionary Districts" and meeting criteria established by the General Convention. Others were formed by the subdivision of a diocese. Others were formed by the combining of dioceses.

A diocese may come to an end in a number of ways. It may be combined with another diocese. It may rejoined with a diocese it originally divided from. It may become its own independent church (e.g. the Diocese of Mexico).

Each diocese carries its own story of formation, life, and sometimes ending. A number of diocesan histories trace these stories. You are encouraged to discover if your diocese has such a history and to delve into it and discover the faith that has been lived out there.