Founded in 1941 as a source of loans and basic savings products, GCS Credit Union has always focused on the member. Through t ... he years, that philosophy has served us well, helping us grow from a single office in Granite City to a full-service financial institution serving the following Illinois counties: Sangamon, Logan, Macon, Marion, Jefferson, Perry, Jackson, Williamson, Jersey, Macoupin, Montgomery, Madison, Bond, Clinton, St. Clair, Monroe, Washington, Randolph. Anyone who lives, works, or attends school within these counties, is eligible for GCS membership. GCS is big enough to offer convenience, but small enough to offer customized financial services to meet your ever-changing needs. We are not pushy and profit driven – we look out for your best interests. It’s what makes banking with a credit union so satisfying. Your Community, Your Needs, Our Focus. GCS Credit Union is Federally Insured by NCUA. read more