Mortgage delinquencies in cities where the economy is dependent upon the oil industry are on the upswing, even as nationwide default rates remain near 10-year lows, CoreLogic said.

For July, 4.6% of all mortgages were at least 30 days or more late on their payment, compared with 4.5% in June and 5.5% in July 2016, according to CoreLogic's Loan Performance Insight Report.

Seriously delinquent mortgages, defined as at least 90 or more days late, were 1.9% of all outstanding loans in July, unchanged from June and down from 2.5% in June 2016.

"Even though delinquency rates are lower in most markets compared with a year ago, there are some worrying trends," said CoreLogic President and CEO Frank Martell in a press release.

"For example, markets affected by the decline in oil production or anemic job creation have seen an increase in defaults. We see this in markets such as Anchorage, Baton Rouge and Lafayette, La., where the serious delinquency rate rose over the last year."

Alaska was the only state where the seriously delinquent rate increased year-over-year, to 1.1% from 1%. North Dakota was flat at 0.9%, while for Louisiana, it fell to 3.4% from 3.5%.

The 30-days-or-more delinquency rate in Anchorage increased to 3.5% from 3.1% last July, while the seriously delinquent rate increased to 1.2% from 1%.

Baton Rouge's seriously delinquent rate increased to 3.6% from 3.1%, while Lafayette's seriously delinquent rate increased to 3.2% from 2.9%. The seriously delinquent rate for Hammond, La., increased to 3.2% from 3%.

The other two cities with year-over-year increases in borrowers 90 days or more late with their payments were Victoria, Texas, at 2%, up 20 basis points, and Casper, Wyo., at 1.8%, up 10 basis points.