In 1921 Col. Brittin and St. Paul banker Richard C. Lilly urged Twin Cities businessmen to buy out the Detroit investors and bring Northwest "home". They were successful and Lilly became Northwest's first "home grown" president. Northwest's first headquarters was at Speedway Field, on the site of present-day Twin Cities International Airport, on the west side of the Mississippi River. In 1930 the headquarters relocated to the St. Paul Municipal Airport (later re-named Holman Field), and St. Paul remained Northwest's home for the next 30 years of its growth.
The year 1928 saw rapid expansion at Northwest. Service began to Fargo and Grand Forks, North Dakota and Winnipeg, Manitoba, Canada. Duluth, Minnesota, and several other North Dakota cities were soon added. Montana cities soon came aboard and in 1933 Northwest achieved its long-sought "Northern Transcontinental" route to the Pacific Coast, when it was granted an extension to Seattle, Washington.