I am interested in majoring in economics, psychology, or political science/government. Which schools are very strong in all these areas?
Lots of schools.
As an undergrad, since you are broadly interested in lots of majors, your goal should not be trying to select a university that has “very strong” department in any particular area. You go to undergrad to get a broad education in liberal arts with a little depth in one field. You really spend most of your time taking classes across other departments. As such, you’re looking for a good overall university. Most good overall universities have good departments in all of those fields.
“Very strong” department hunts are for graduate school, when you know exactly which department you’ll be in AND you spend close to 100% of your academic and professional time in that department.