Most U.S. states have a unified (mandatory) bar association to which all attorneys must belong in order to practice in that state. Some states have voluntary bar associations to which attorney may belong, but they do not have to be a member of the bar in that state in order to practice in the state.
The states which have mandatory/unified/integrated bar associations:
Alabama, Alaska, Arizona, California, Florida, Georgia, Idaho, Kentucky, Louisiana, Michigan, Mississippi, Missouri, Montana, Nebraska, Nevada, New Hampshire, New Mexico, North Dakota, Oklahoma, Oregon, Rhode Island, South Carolina, South Dakota, Texas, Utah, Virginia, Washington, West Virginia, Wisconsin, and Wyoming. The District of Columbia, the U.S. Virgin Islands, Puerto Rico, Guam and the Northern Mariana Islands also have mandatory bar associations.
