In the three-and-half decades since enactment of the 1978 Airline Deregulation Act, airfares have plummeted in real terms. That reduction in price includes those dreaded fees for baggage, seat upgrades, etc., which make up only a small fraction of consumers' overall cost of travel.
But beginning in 2009, fares began to creep up, as indicated in the chart below.
With that in mind, read this article by Steven Pearlstein explaining why the U.S. Justice Department has gone to court to block the proposed U.S. Airways-American merger.
The Justice Department has put together a nice graph (below), which provides a time line of U.S. airline consolidation from 2005 to the present. In 2005, there were 9 major domestic airlines. Today, there are 5.