If President Trump wants to cast doubt, he might pick a target that is less easily measured than crowd size. We can count people. People take up space. Here’s a rule of thumb, explained by Professor Steve Doig of Arizona Statue University.
A loose crowd, one where each person is an arm’s length from the body of his or her nearest neighbors, needs 10 square feet per person. A more tightly packed crowd fills 4.5 square feet per person. A truly scary mob of mosh-pit density would get about 2.5 square feet per person.
Read more about it via How big will inaugural crowd be? Do the math – politics – Inauguration | NBC News.