In the 2009 flu pandemic, the virus isolated from patients in the United States was found to be made up of genetic elements from four different flu viruses – North American Mexican influenza, North American avian influenza, human influenza, and swine influenza virus typically found in Asia and Europe – “an unusually mongrelised mix of genetic sequences.”[13] This new strain appears to be a result of reassortment of human influenza and swine influenza viruses, in all four different strains of subtype H1N1.

Below is the Google Map of the situaion of US and Canada:
h1n1-flu-us-canada

On June 11, 2009, the WHO declared an H1N1 pandemic, moving the alert level to phase 6, marking the first global pandemic since the 1968 Hong Kong flu. (http://en.wikipedia.org/wiki/Influenza_A_virus_subtype_H1N1)