The average airfare from Charleston International dipped below the $400 level in the 2013 fourth quarter, a new federal report says.

The U.S. Department of Transportation said that South Carolina's busiest airport was ranked No. 40 in terms of highest domestic ticket prices among the top 100 airports in the country.

The average fare at Charleston International was $396.91 for the October-December period, down almost 7 percent from the same quarter of 2012.

Local airline prices have been falling in recent years as more competitors have entered the market, even as major carriers serving the airport have merged. The most recent newcomers to Charleston are Southwest Airlines and JetBlue.

Nationwide, the average domestic airfare rose to $381 in the fourth quarter of 2013, a 0.3 percent increase from a year earlier, the report says.

The No. 1 most expensive U.S. airport for travelers at the end of last year was in Huntsville, Ala., where fares averaged $527. The cheapest was Long Beach, Calif, near Los Angeles. Its average domestic ticket price was about $249.

The only other S.C. airport among the top 100 was No. 63 Greenville/Spartanburg International. Its average fare was down 7 percent in the fourth quarter to $372.

The Transportation Department figures, which are adjusted for inflation, mostly count round-trip fares, but about a fourth are one-way trips if that's what the passenger bought. Taxes are included, but bag fees and other services are not.

"The base fare may not be much higher, but because of the add-ons, it feels worse," said Rick Seaney, CEO of travel site FareCompare.com.

The Associated Press contributed to this report.