46% of Americans are Young Earth Creationists, 58% of Republicans:
From Charles Johnson:
Most Americans are not scientists, of course, and cannot be expected to understand all of the latest evidence and competing viewpoints on the development of the human species. Still, it would be hard to dispute that most scientists who study humans agree that the species evolved over millions of years, and that relatively few scientists believe that humans began in their current form only 10,000 years ago without the benefit of evolution. Thus, almost half of Americans today hold a belief, at least as measured by this question wording, that is at odds with the preponderance of the scientific literature.