Via CNN

According to a study by the National Health and Social Life Survey, the U.S. circumcision rate peaked at nearly 90 percent in the early 1960s but began dropping in the '70s. By 2004, the most recent year for which government figures are available, about 57 percent of all male newborns delivered in hospitals were circumcised. In some states, the rate is well below 50 percent.

More at the link above.