Green River Basin Federal Credit Union has been open since 1967. It's the 22nd largest credit union in Wyoming with assets totaling $11.97 Million and providing banking services to more than 2,000 members. Membership: The credit union is a community-based financial institution. People living, working, or worshipping in the credit union's geographic area can become a member and access banking services. Membership is also open to immediate family of current members.