Actually, Delta's name does have a geographic tie...to the Mississippi River Delta. From Wikipedia:

The company has its roots in Huff Daland Dusters, which was founded in 1924 in Macon, Georgia by several partners including Collett E. Woolman becoming the world's first aerial crop dusting company. Huff Daland moved to Monroe, Louisiana the following year. In 1928, Huff Daland Dusters was purchased by C.E. Woolman and renamed Delta Air Service after the Mississippi Delta, where its route connected Dallas, Texas to Jackson, Mississippi, via Shreveport and Monroe. The original directors of Delta Air Service were C.H. McHenry, Travis Oliver, and M.S. Biedenharn. By 1934, Delta began mail service from Charleston to Fort Worth, with stops in Columbia, Augusta, Atlanta, Birmingham, and Meridian along the way.[citation needed]