Explore the 23 California State University campuses on foursquare! From Humboldt State in the north to San Diego State in the south, we will be leaving tips all throughout California. Learn about the history, culture and fun tidbits about each campus. The California State University is the largest system of senior higher education in the country, with 23 campuses, approximately 412,000 students and 43,000 faculty and staff. The mission of the CSU is to provide high-quality, affordable education to meet the ever changing needs of the people of California.