On November 22, 1935, the China Clipper made its first airmail voyage across the Pacific Ocean. Aviation in the 1920s developed at an incredible pace. Instead of the fragile wood and fabric of early biplanes, aircraft were soon being constructed of sturdy, streamlined metal propelled by increasingly light and powerful motors. As planes became more safe and reliable, people began to realize the amazing potential of flight. US Airmail, first flown in May 1918, began regularly scheduled transcontinental flights only two years later. Commercial travel developed alongside airmail, bringing passengers to their destinations quicker and easier than ever before. But as fast as flight was progressing, the oceans still proved a formidable obstacle.