Why are most top engineering schools large state schools?

How do you know if a college has a good engineering department? Is accreditation all you need to be considered a good engineering school?

Also, someone mentioned how size at first glance isn’t everything. Would a college with a large total enrollment, but a relatively low number of engineering majors be the same as going to a small college? I understand that most of my first classes will have several hundreds and there is no way around that. However, I feel like it would different at a school like Bucknell.