Consumer confidence increased steadily between July and September, as hiring improved, particularly in August and September. Employers added 171,000 jobs in October.
Another likely contributor to the rise in card balances is that banks have been issuing more cards to borrowers, including those with less-than-sterling credit.
Data on the number of new credit card accounts opened by consumers lags by a quarter, so the most recent figures that TransUnion reports are from the second quarter of this year.
The data show that the number of new cards issued by banks rose 3.1 percent in the second quarter from a year earlier, with more than a quarter of the cards going to consumers with a nonprime credit score, according to the VantageScore credit scale.
A nonprime score is anything below a 700 on the scale, which ranges from 990 to 501. The lower the score, the more of a credit risk a borrower represents to banks.
All told, 29.6 percent of the cards issued by lenders in the third quarter went to nonprime borrowers.
"Lenders are absolutely issuing more credit in the nonprime space," Becker said. "The size of the pie is bigger and nonprime consumers are getting a larger share of that pie."
Banks have become more open to issuing credit cards to higher-risk borrowers due to tight competition for top-rated consumers, many of whom are not signing up for additional credit. That leaves the crop of borrowers with some blemishes in their credit history.
Even so, TransUnion forecasts that severe delinquency rates on cards will remain near current low levels in the fourth quarter.