Harvard has a 3% acceptance rate. California Institute of Technology with a 3% acceptance rate. According to Niche, these are the hardest colleges to get in to in Iowa, Wisconsin, and Minnesota. This small Iowa liberal arts college has a low 13 percent acceptance rate. Google Earth Google EarthLocated in Northfield, this highly rated private college enrolls just over 2,000 full-time undergraduates with an acceptance rate of just 22 percent.