The helpful previous replies gave me an idea for a Google search, and I found several regional association of college admission counselors with websites listing upcoming college fairs.
Hawaii Association
HACAC College Fairs
Minnesota Association
MACAC
New England Association
Spring Fair Schedule - NEACAC
Pacific Northwest Association
College Fairs
Pennsylvania Association
PACAC
Rocky Mountain Association
RMACAC.ORG - The Rocky Mountain Association of College Admission Counseling
Western Association
WACAC