The proposed rule would also allow applicants seeking approval to initially form, expand or convert to a community charter the option of submitting a narrative to establish the required common bonds instead of relying on a "presumptive community" standard.

The NCUA received 11,380 comments on the proposed rules, with commenters generally supporting them by a ratio of about three to one.

However, banking groups voiced their opposition to many of the provisions. The Independent Community Bankers of America has made it clear it will sue the NCUA if it does not like the rules.

Many of the provisions of the rule were included in the proposed rule issued last year. However, the NCUA did not include a provision defining a congressional district as a well-defined local community.

Under the final rule approved Thursday:

• Federal credit unions will now be permitted to apply to convert to a community charter or expand an existing charter without serving the core area if they elect to serve a portion of a core-based statistical area. "This will allow a federal credit union to establish a presence consistent with its ability to serve before expanding service to the full area," the agency said.

• The NCUA's population limit of 2.5 million people will apply to any well-defined portion of a core-based statistical area regardless of the whole area's population.

• Federal credit unions will be able to serve a Combined Statistical Area as defined by the Office of Management and Budget, subject to the 2.5 million population cap.

• Federal credit unions may only serve a rural district in those states bordering the state containing the credit union's main office.

• The NCUA will use the CFPB-designated "underserved county" as an underserved area.

• Multiple-bond credit unions will have parity with single common-bond credit unions in serving contactors.

The NCUA staff said that federal law does not impose for any of the three community categories a maximum limitation on population or geographic size.

"We need to make it easier for people to access affordable financial services," Metsger said.

He added, "To the best of my knowledge, no credit union has ever failed because its Field of Membership was too large. But some credit unions have failed because it was too small."