The transportation sector lies in the crosshairs of the current economic debate. Hopeful bulls are anticipating a surge in industrial activity during the second half of the year while nervous bears expect planes, trains and automobiles to carry lighter loads well into 2010, with slack demand affecting the entire spectrum of goods, services and travel.The broad sector is actually composed of four smaller groups, each with unique exposure to the economic cycle. Airlines, railroads, packaging and shipping companies traveled a similar path during the historic bear market to multiyear lows, but their performance has diverged sharply in the last five months. Let's see how this diverse behavior has created new trading opportunities. The Dow Jones Transportation Average Index Fund ( IYT) sold off in three waves between June 2008 and March 2009, coming to rest at a multiyear low near 38. It surged higher for the next eight weeks, hit the 200-day moving average and dropped into a broad sideways pattern that's still in place as we head into the dog days of summer.