An alcalde was, in the absence of a corregidor, the presiding officer of the Castilian cabildo (the municipal council) and judge of first instance of a town.
[3] Alcalde was also a title given to Indigenous (Native American) leaders inside the Spanish missions, who performed a large variety of duties for the Franciscan missionaries.
As fortified settlements in the area between the Douro and Tagus rivers became true urban centers, they gained, from their feudal lords or the kings of Leon and Castile, the right to have councils.
The council was limited to a maximum of twenty-four members (regidores), who may be appointed for life by the crown, hold the office as an inherited possession or be elected by the citizens (vecinos) of the municipality.
The number of magistrates, now definitely called alcaldes, was limited to one or two, depending on the size of the city and who were elected annually by the regidores.
Early in the conquest, adelantados had the right to appoint the alcaldes in the districts they settled, if they could attract the legally specified number of settlers to the area.
In modern Spanish, the term alcalde is equivalent to a mayor, and is used to mean the local executive officer in municipalities throughout Spain and Latin America.
Because the United States incorporated parts of the former Viceroyalty of New Spain, the office had some influence in the local political and legal developments of those areas and is mentioned in judicial cases.