Even though the digital world is eating away at branch traffic, credit unions are plowing dollars into branch construction anyway, according to a study by SNL Financial, leaving many credit union execs debating over the highest and best use of their expansion capital.

Branch transaction activity is roughly half what it was in 1992, according to the FDIC, and check use is barely a third of what it was in 2003. But SNL found that the total number of credit union branches rose for a second consecutive year; as of July 30, there were 27 more opened than closed in the United States. That may seem small, but it's a big difference from the 241 net branches lost in 2012 and 2013.

Navy Fed, which ranked first in SNL's list of 2015 net openings, has added 13 new branches so far in 2015 and expects to open seven more by the end of the year, Kathy Ward, senior vice president of branch operations at the Vienna, Va.-based Navy Federal Credit Union, said.