Membership in BACU is open to anyone who lives or works in the Illinois counties of Carroll, JoDaviess, Lee, Ogle, Stephenson and Whiteside. In addition family members of current members are eligible for membership no matter where they live. "Family members" include spouses, parents, grandparents, children and legal dependents, brothers, sisters and their spouses, grandchildren, aunts, uncles, nieces, nephews, cousins and sons- and daughters-in-law.