NOTE: The estimated Spanish-surnamed registered voters in the following tables were produced by performing queries using two different Spanish-surnamed lists. The number of Spanish surnames on the list use to conduct the query impacts the total of Spanish-surnamed registered voters produced.
The Spanish-surnamed totals in the green and orange tables are based on a query conducted with a list of the most frequent heavily used 639 Hispanic surnames. This query produces a very conservative estimate of Spanish-surnamed registered voters.
The Spanish-surnamed totals in the red and blue tables are based on a query conducted with a list of over 12,000 Spanish surnames. This query produces a generous estimate of Spanish-surnamed registered voters.
Based on the totals produced, it is very likely that number of Spanish-surnamed registered voters falls somewhere between the high and the low produced by the queries. Keep in mind that in Harris County, the Citizen Voting Age Population (CVAP) is 27% Hispanic or Latino, 22.5% Black or African American, 43.1 % White and 6 % Asian. That is the percentage each major voting group would reach if all the County’s CVAP was 100% registered to vote.
Regardless of the surname list employed to conduct the queries on the voter registration roll, the analysis shows that the percentage of Spanish and Asian surname registered voters is increasing throughout Harris County while the percentage for the other major voting groups is decreasing. 
