Flying was long thought of as a luxury beyond the reach of the average American. That changed as the industry matured and a greater number of airlines emerged to service budget-conscious travelers, which brought about a welcome drop in prices.

But some tickets still remain more expensive than others. The Department of Transportation tracks which routes in the U.S. have the costliest fares, along with which airlines have the biggest market share along those routes.

Click through to see which airline routes were the most expensive during the second quarter of this year.