Mexican localidad code

Nine digits: two for the state, three for the municipality and four for the locality within it. 301510002 is a rural locality in Tamiahua, Veracruz.

A locality is a settled place rather than a unit of government, and most are small. The key is the least stable of the three INEGI levels, because rural localities are merged and dissolved between censuses.

The first five digits are the Mexican municipio code the locality belongs to, so the municipality follows from the key without a second lookup.