Census Records
Spanish and Mexican
Spanish and Mexican colonial censuses can be found at the New Mexico State Records Center and Archives. Two helpful books on the subject are:
Spanish and Mexican censuses of New Mexico, 1750-1830 by Virginia Langham Olmsted
Spanish and Mexican colonial censuses of New Mexico, 1790, 1823, 1845 by Virginia Langham Olmsted
United States
United States Census records from 1790 to 1940 are available online for free at FamilySearch.org.
Here are some other, Socorro area-specific, resources:
United States of America, 1910 Territorial Census for the Territory of New Mexico, Every Name Index of Socorro County, New Mexico
1940 Census Enumeration District Maps: New Mexico: Socorro County
1940 Census Enumeration District Descriptions: New Mexico: Socorro County
1950 Census Enumeration District Maps: New Mexico: Socorro County