I'm sorry this took so long to answer. The US Federal Government does not run any hospitals except for the military, and the Veterans Administration. Others are run by private companies, or non-profit groups, many are run by Universities that also do medical research, and there are some that are run by state and local governments. Most are not free if you can afford to pay, none can turn you away if you seek treatment for an emergency.
The Shriner s Hospital in Tennessee is a children hospital that treats cancer and leukemia in children free of charge.
I hope that helps my freind email me if you need more information.