I know at Columbia University, you do not declare your major until after sophomore year. Are there any other prominent universities that also do this?
At Columbia, you can declare your major at any time up to the end of your sophomore year. That is the way it is at most major universities in the country.
However, in practice many students declare their major before the end of their sophomore year for various reasons. For most majors - even social sciences and humanities majors - if you wait until junior year to begin taking classes, you may not graduate in 4 years. And with science majors, foreign language majors, some arts majors (like music), and probably some other ones I’m not thinking of, you must begin taking a specific sequence of classes in your freshman year in order to graduate in 4 years.