Janie, these are just general figures on Hispanics from the internet, but they are important. Not what you are after? I'm not sure what kind of demographics you want- race, income, education- Best compiled state by state.

Hispanics in the United States- over 44 million, making it the largest Hispanic concentration after Mexico.
The article in Wackipedia estimates 28 million speak Spanish at home.

California, Arizona, New Mexico, Texas have more than 30% Hispanics.
New York has a very large Hispanic community, estimates put the numbers of Dominicans alone at over 590,000 (Estimate from State University of NY analysis). Total NY abt. 3 million.
Much bad feeling in Arizona as a result of the English official language law recently passed.

New Mexico has constitutional protection for Spanish-speakers, and has always published or made available the laws in Spanish. All California laws are available in Spanish. Some southern counties in Texas are largely Hispanic.

Candidates will have to woo these voters.