Yesterday was National Aviation Day, a holiday established by president Franklin Delano Roosevelt in 1939 to celebrate developments in aviation. The date selected was the birth date of aviation pioneer Orville Wright, who, along with his older brother Wilbur, is credited with inventing and building the world's first practical fixed-wing aircraft and making the first controlled, powered and sustained flight more than a hundred years ago. The Wright brothers documented much of their early progress in photographs made on glass negatives. Today, the Library of Congress holds many of these historic images, some of which are presented below.