Why does it seem like the Swine flu is worse in Mexico than the US?

It seems that it may have gotten started there and so it has had more time to infect more people. It could also be that the general state of health of the urban Mexican people left them more susceptible compared to the US. A large part of the cases in Mexico are in Mexico City where the population is very dense, making it easier for the spread of the virus among the people on the very crowded streets and family groupings. But until more time passes and more study is done on this new strain of flu, we won't have any definite answers...stay tuned.