Use the preferred nationality in ULAN if the artist has a record. Note, you may have to search the English equivalent of a name in ULAN.
If there is no record for the artist in ULAN, search LOC Authorities for a name heading and use American if they were born in the United States. Use Mexican if the artist was born in Mexico, or other appropriate nationality if the artist was born in another country (e.g. Guatemalan).
Repeat Nationality from Artist Record for culture. When applicable repeat the culture field and include any of the following…
Use Hispanic American for residents of the United States of Latin American or Spanish origin (this includes Mexican Americans).
Use Mexican American for Chicano/Chicano Artists and Americans of Mexican descent.
Use Latin American for artists from the countries of South America, North America (Mexico), Central America, and the Caribbean that were originally colonized by Spain.
There is some useful information on the artists in Contemporary Chicana and Chicano Art on the website: http://latinoartcommunity.org/community/ChicArt/ArtistDir.html