BANGOR, Maine, April 29 -- The U.S. Department of Homeland Security's Transportation Security Administration issued the following news release: Nationally, the number of passengers expected to fly this spring and summer is expected to be the highest in years with more than 2.3 million passengers per day expected to pass through Transportation Security Administration checkpoints during the popular spring and summer travel period. During the month of April, TSA expects to see checkpoint volume gr  more