College campus still opened in USA ?

Many college campuses are still open in the US - most with limited capacity or significant restrictions.  However, a majority of the biggest ones are closed completely and only allow for online classes because they are in states run by leftist governors.  One of the schools is slated to be online only until January, while another at which I am teaching online also has face to face classes (and if I get the full time position I applied for, I would be teaching in person in August).

It depends on the University or college and wither a?specific campus has limited access or not. Yes. many universities?are in session with live face to face classes. You can w/o onto the?University of Oklahoma Norman campus. Very Lily you can do that at the Tulsa campus. Tulane's uptown campus has somewhat limited?access to part of the campus. The medical school and hospital  downtown is open but I suspect if you go to the medical school, your ID is thoroughly checked. 

in America, the Federal government has no authority to close all universities, or even all public schools.  Only the states might have such authority -- and many have declined to do so [plus there are those that lack the authority because pandemic or epidemic conditions were not anticipated in state law]

It varies from school to school. At my university, students were able to move back into the dorms in Septembers, and there were some classes meeting in the fall. We have more classes meeting now- sometimes the teacher meets with half the class on one day and half on another to allow distancing. But rates of transmission are going down rapidly, and we will probably have more classes on campus in the summer and fall. 

Different universities implemented different policies.  One of my grandson's school's is completely online.  At the other's college, hybrid (mixed in-class and virtual) is used.

Some campuses are at least partially open.  Most of the freshmen, laboratory, and graduate courses at my university are being taught in-person.  Some students still live on campus, in Greek housing, or in local apartments.  Some did choose to stay home and do their courses online.  Some universities have no in-person courses right now while others have quite a few.