The company was incorporated in Seattle, Washington by William E. Boeing on July 15, 1916, as “Pacific Aero Products Co.” following the June 15, 1916 maiden flight of one of the two “B&W” seaplanes built with the assistance of George Conrad Westervelt, a U.S. Navy engineer. On May 9, 1917, the company became the “Boeing Airplane Company”. William E. Boeing had studied at Yale University and worked initially in the timber industry, where he became a rich man and acquired knowledge about wooden structures. This knowledge would prove invaluable in his subsequent design and assembly of airplanes.

In 1927, Boeing created an airline, named Boeing Air Transport (BAT). A year later, BAT, as well as Pacific Air Transport and Boeing Airplane Company merged into a single corporation. The company changed its name to United Aircraft And Transport Corporation in 1929 and acquired Pratt & Whitney, Hamilton Standard Propeller Company, and Chance Vought. United Aircraft then purchased National Air Transport in 1930. The Air Mail Act of 1934 prohibited airlines and manufacturers from being under the same corporate umbrella, so the company split into three smaller companies - Boeing Airplane Company, United Airlines, and United Aircraft Corporation, the precursor to United Technologies. As a result, William Boeing sold off his shares.

During World War II, Boeing built a huge number of bombers. Many of the workers were women whose spouses had gone to war. In the beginning of March 1944, production had been scaled up in such a manner that over 350 planes were built each month. To prevent an attack from the air, the manufacturing plants had been covered with greenery and farmland items. During these years of war the leading aircraft companies of the US cooperated. The Boeing-designed B-17 bomber was assembled also by Lockheed Aircraft Corp. and Douglas Aircraft Co., while the B-29 was assembled also by Bell Aircraft Co. and by Glenn L. Martin Company.

Boeing 377 Stratocruiser

After the war, most orders of bombers were canceled and 70,000 people lost their jobs at Boeing. The company aimed to recover quickly by selling its Stratocruiser, a luxurious four-engine commercial airliner developed from the B-29. However, sales of this model were not as expected and Boeing had to seek other opportunities to overcome the situation. The company successfully sold military aircraft adapted for troop transportation and for aerial refueling.