LOS ANGELES — More Americans fell behind on their auto-loan payments in the third quarter, when back-to-school shopping and other needs traditionally put a strain on consumers’ wallets.

But the uptick is likely only a seasonal blip in an otherwise multiyear decline in auto-loan delinquencies, reporting agency TransUnion said today.

The rate of U.S. auto-loan payments at least 60 days overdue rose to 0.38 percent from 0.33 percent in the second quarter, the company said.

That represents only a slight uptick from the second quarter, which marked the lowest delinquency rate on TransUnion’s records going back to 1999.

The July-to-September delinquency rate also was down 19 percent from the 0.47 percent rate a year earlier, the firm said.

All told, the auto-loan delinquency rate has fallen on an annual basis for 12 consecutive quarters.

“Based on the data, this looks like it’s attributed to really just the seasonal factors,” said Peter Turek, a vice president of TransUnion’s financial services business unit.

Since the housing collapse in 2007 and recession that followed, many borrowers have made keeping up with car payments a priority above paying their mortgage or other financial obligations.

Other factors also have influence the trend, including low interest rates on loans, which have made financing more affordable. A strong market for used cars also has also played a role.