Further subdivision into 828 registration districts and 3,751 district electoral divisions followed. Townlands were not arranged according to these divisions with parish and barony retained as a means to make comparisons with records gathered before 1898. As the population grew, new parishes were created and the civil parish covered the same area as the established Church of Ireland. The Roman Catholic Church adapted to a new structure based on towns and villages. The boundaries have remained virtually intact and are used by both Catholic and Anglican churches.
Dioceses have little relation to county boundaries.
It is the Church of Ireland dioceses as they existed in the mid-19th century that are mapped here. In 1858 a principal registry and eleven districts were established for the purpose of proving wills and granting administrations. Remnants survive for some parts, but the year 1901 is the first year for which a complete census return for all Ireland exists. The Griffifth's is a comprehensive record that lists all property holders, no matter how insignificant the amount of land or size of house occupied. It may be the last official record of many emigrants.