American Airlines is a major American airline headquartered in Fort Worth, Texas, within the Dallas-Fort Worth metroplex. It is the world's largest airline when measured by fleet size, revenue, scheduled passengers carried, scheduled passenger-kilometers flown, and number of destinations served. American, together with its regional partners, operates an extensive international and domestic network with an average of nearly 6,700 flights per day to nearly 350 destinations in more than 50 countries. American Airlines is a founding member of Oneworld alliance, the third largest airline alliance in the world. Regional service is operated by independent and subsidiary carriers under the brand name American Eagle. American Airlines was started in 1930 via a union of more than eighty small airlines. The two organizations from which American Airlines was originated were Robertson Aircraft Corporation and Colonial Air Transport. The former was first created in Missouri in 1921, with both being merged in 1929 into holding company The Aviation Corporation. This in turn, was made in 1930 into an operating company and re-branded as American Airways. In 1934, when new laws and attrition of mail contracts forced many airlines to reorganize, the corporation redid its routes into a connected system, and was renamed American Airlines. Between 1970 and 2000, the company grew into being an international carrier, purchasing Trans World Airlines in 2001.