With almost 23,000 employees and an annual federal payroll of $1.8 billion, Robins Air Force Base in Warner Robins is clearly the economic engine of Middle Georgia.

But the midstate’s diversity is displayed in its other largest employers -- a public-private mix that includes school systems and universities, city and county governments, health care systems, aerospace industries, a bus maker and an insurer known for its clever TV advertising.

Here is a list of the area’s 25 largest employers:

Robins Air Force Base 22,911

The Medical Center of Central Georgia 6,200

GEICO 4,700

Houston County Board of Education 3,720

Bibb County Board of Education 3,700

Houston Healthcare 2,352

Perdue Farms 2,087

Frito-Lay 1,432

Coliseum Health Systems 1,300

City of Macon 1,250

Engelhard Corp. 933

Mercer University 881

Bibb County 770

Fort Valley State University 756

YKK U.S.A. 750

Wal-Mart Superstores (Macon-Bibb County) 726

City of Warner Robins 673

Houston County 650

Academy Sports distribution center 625

U.S. Postal Service 600

Ricoh USA 575

Boeing 544

Georgia Farm Bureau Federation 525

Northrop Grumman 500

Armstrong World Industries 405

-- Source: Robins Air Force Base, Macon Economic Development Commission, Robins Regional Chamber of Commerce, City of Warner Robins and Fort Valley State University.