Delta Air Lines, headquartered in Atlanta, is a global aviation giant operating over 5,400 daily flights to 325 destinations across 52 countries, with its largest hub at Hartsfield-Jackson Atlanta International Airport. As one of the oldest US carriers, it traces its roots to the world's first crop-dusting company, Huff Daland Dusters (founded 1925), and began passenger service in 1929 under the leadership of C.E. Woolman. A founding member of the SkyTeam alliance, Delta ranks first globally in revenue and brand value, and second in passengers carried. Throughout its history, Delta expanded through major acquisitions (Northeast, Western, and Pan Am's trans-Atlantic routes) and pioneered new aircraft, being the first to fly the DC-8, DC-9, and MD-11. In 1997, it became the first airline to board over 100 million passengers in a single year, cementing its status as an industry leader.