What would United States colleges do without adjunct instructors?

Adjunct is a fancy word for part-time, and there are small private colleges, especially those of the vocational school variety, not to mention others such as John F. Kennedy University in Pleasant Hill, whose part-time faculty far outnumber the full-time faculty. When I worked for De Anza College, their English Department had almost twice as many part-time as full-time instructors. We are cheaper, we don't always demand offices and campus voice mail, and we might actually teach more classes than a full-time instructor.