Official data in India are mostly published at the state or district level. Multi-year analyses of these data are made difficult by the many changes in state and district boundaries that have occurred since the first comprehensive census of independent India in 1961. Between 1961 and 2001, the number of states and union territories in India increased from 26 to 35, and the number of districts increased from 339 to 593. There were several changes in both names and boundaries. We document these changes and use them to construct regions of amalgamated districts with constant boundaries.
