It's a well-known fact that the Earth is round and I can show you evidence with about two seconds of Googling.
You established that a well-known fact like the Earth being round is easy to prove in mere seconds by Googling. I did exactly what you suggested and the search results are plentiful with links in the first page confirming that there's a left-leaning bias in USA universities. In the suggested images they even list survey results showing most students lean left.