Twenty four suspected cases and three deaths were also recorded in San Luis Potosi in central Mexico.
The above comment confirm that the swine H1N1 in southwestern United States (see updated map) is the leading edge of a H1N1 pandemic that appears to be centered in Mexico.
Updated information about the investigation in US: CDC web site
http://www.recombinomics.com/News/04240901/H1N1_Swine_Mexico.html