Credit unions in the U.S. added 5.2 million members in 2021, despite a decline in the total number of these financial institutions.

Membership at credit unions increased 4.1% year over year and 0.6% quarter over quarter to 130.8 million as of Dec. 31, 2021, according to S&P Global Market Intelligence data.

Aggregate trend over the years

Increase in membership and a decline in total number of credit unions helped elevate the average number of members per credit union to 25,922 in 2021, up from 24,139 in 2020. Over the last five years, average credit union membership has increased by over 7,600.

Vienna, Va.-based Navy FCU, the largest credit union by assets in the U.S., reported 11.1 million members at Dec. 31, 2021, a 12.2% increase from the previous year and a 2.2% gain from the linked quarter.

Tysons, Va.-based Pentagon FCU, the third-largest credit union by assets, posted the largest year-over-year growth of 18.4% in membership among the top 20 U.S. credit unions. In April 2021, PenFed absorbed two smaller credit unions — Madison, Wis.-based Post Office CU and Clark, N.J.-based Aspire FCU — which together reported almost 23,000 members as of March 31, 2021.

San Antonio, Texas-based Security Service FCU was the only credit union among the top 20 that reported both a year-over-year and quarter-over-quarter decline in members. The credit union's membership declined 0.6% from the previous year and 0.3% from the linked quarter to 799,000.