Delta Air Lines will end daily flights from Sioux Falls to Salt Lake City on Jan. 8, but service will continue between Rapid City and Salt Lake City, according to SkyWest Airlines, the affiliate that operates both routes.

Marissa Snow, spokeswoman for SkyWest, said Friday that no changes are planned for Delta Connection service to Rapid City.

Sioux Falls Regional Airport executive director Mike Marnach said the Sioux Falls-Salt Lake City Delta Connection flights, which began in June 2006, have not drawn as many passengers as expected. The planes were about 60 percent full in 2007, and about 77 percent full during summer months.

Delta's flights from Sioux Falls to Cincinnati and Atlanta remain strong, and overall boardings in Sioux Falls are up 9 percent.

Bentonville, Ark., also is losing its Salt Lake City flights. In a news story about that loss, a Delta spokeswoman said the cuts are part of a 5 percent decrease in services system-wide.

Although Rapid City service is not being cut, the Delta Connection load factors - the percentage of seats filled by passengers - have been similar to those in Sioux Falls. Load factors ranged from 48 percent in January to 86 percent in June. The 11-month average in 2007 was 67 percent.

The Delta route between Rapid City and Salt Lake City has carried a little more than 66,000 passengers through the end of November, according to airport records. That is fewer passengers than United Express and Northwest Airlines, the other carriers that have served Rapid City with daily flights throughout 2007. United Express flies to Denver, and Northwest flies to Minneapolis.

However, Delta Connection traffic was up 6 percent in October and November, compared with the same period in 2006.

And Rapid City air travel overall has been increasing. Rapid City Regional Airport saw a 21 percent surge in airline traffic during October and November, due in part to new service.

Frontier Airlines, the Denver-based low-fare carrier, began twice-a-day service between Rapid City and Denver on Oct. 5. Allegiant Air added a nonstop flight to the Phoenix-Mesa area Nov. 21.

Before Frontier hit the market, there were concerns that the new carrier would take passengers away from the other carriers. But only Northwest Airlines has seen a dip in passenger service.

The Associated Press contributed to this report.