In the spring hundreds of bird species move from the tropics into North America. As they make their way they eventually face the great barrier of the Gulf of Mexico. This arm of the Atlantic Ocean is more than 900 miles wide, and more than 600 miles across from north to south. While some birds skirt the edge of the water, the overwhelming majority-more than 200 species, and hundreds of millions of individuals-cross the unbroken plain of the gulf in a single flight of 20 or more hours. Gulf Crossing is a record of trans-gulf migration on America’s southern coast: the expectation of arrival, the surprise each day of what birds appear, and the habitats they are found in. The experience is expanded by a scientific perspective on the phenomenon of migration, describing it's geographic shape, the coastal habitats birds rely on, physiological cycles in birds, and the effect of weather patterns on bird flight.