As the U.S. economy remains in a prolonged slump, more people are turning to online higher-education institutions and community colleges to further their learning and improve their job prospects.

Federal statistics show that of the 20 higher-education institutions with the largest enrollments in fall 2009, five are predominantly online operations and another five are predominantly two-year community colleges.

And those five online campuses—University of Phoenix, Kaplan University, Strayer University, Ashford University and Liberty University—accounted for the largest jump in enrollment among the top 20 colleges; compared with fall 2008, each of them saw student numbers rise by at least 19 percent.

In total, enrollment at the top 20 higher-education institutions was 1,366,980 in fall 2009; online schools accounted for 43.8 percent of those students. Community college systems accounted for another 18.4 percent.

University of Phoenix once again had by far the largest headcount of students—more than 380,000, a jump of 78,909 students in one year. Ashford University, headquartered in Iowa, had the largest percentage increase of students from 2008 to 2009; its count of 46,835 represented a nearly 83 percent increase over the previous year.

The boom in online enrollment is no surprise during economic hard times. Enrolling in and completing online courses may be less costly for students, especially when transportation and housing expenses are considered. The widespread availability of online access and resources, and the continual improvements in technology have made the online learning experience more appealing for many.

People out of work or underemployed may turn to online courses for job retraining or to boost their credentials. The flexible schedules of online courses may attract non-traditional students whose needs aren’t met by daytime classes in hard-to-reach campuses.

For many of the same reasons, community colleges are experiencing enrollment growth. They typically are less expensive, have more flexible schedules, and appeal to non-traditional college students, such as adults who may be switching career fields and seeking job retraining.

All five community college systems in the top 20 experienced enrollment growth from 2008 to 2009. The Houston Community College System saw the fastest increase—a 14 percent hike.

Texas, the nation’s second-largest state, had the most institutions in the top 20: three community colleges (Houston Community College, Lone Star College system and Tarrant County College District), as well as the University of Texas at Austin and Texas A&M University.

Five of the top 20 colleges were not on the 2008 list: Ashford, Liberty, Tarrant County, Lone Star and the University of Washington. The five institutions that fell from the top 20 were University of Illinois, New York University, University of Wisconsin, Purdue University and University of South Florida.

The nation’s largest state, California, has no higher-education institutions in the top 20. UCLA had the largest enrollment in the state in fall 2009 with 38,550 students; that placed it 35th on the list of largest enrollments. But California did have eight institutions with enrollments greater than 35,000 that were among the 50 largest enrollments in fall 2009.