Minnesota. It is called PSEO. If a student scores above some threshold on standardized testing and is in the top third of their class in high school they qualify to enter college as a Junior in high school.

Some students just take a handful of college classes while others like my daughter attend FT and get their freshman and sophomore years of college done while still in high school. And, the state of Minnesota pays full tuition as well as books. It is a great deal for hardworking capable students who are willing to take on regular college work and expectations 1 or 2 years early.