He pointed to statistics that showed the U.S. government AP test was taken by 282,571 students nationally in 2015, compared to just 129,323 in 2005 and 45,328 in 1997.

If they already got credit for the AP exam, students don't take the intro course at UW, Canon said.

Another factor, he said, was the department's shrinking of discussion sections about seven years ago from 22 students to 17.

"Given that there has not been an increase in funding for teaching assistants to compensate for the decline in the size of the sections, the number of available seats in the overall course was reduced," Canon wrote in an email. "While this change was made to improve the quality of teaching, it also was done to remain competitive with our peer institutions. Our graduate students were working more for less pay than our competitors, so this was one way we could try to remain more competitive."

Canon added that a shrinking of intro to American politics courses is a trend wider than just at the UW. Even though its numbers are falling, UW's political science department still awards one of the highest numbers of degrees at the university.