Gage was born on the 80-acre family farm at 9th and Cleveland. He graduated from the University of Kansas in 1907 and became a lawyer following the footsteps of his father to become a lawyer.
In 1930 he started the Gage and Hill law firm in the Bryant Building at 11th and Grand. Following a series of mergers the firm would become Lathrop and Gage, which according to its website is the oldest law firm west of the Mississippi River founded in 1873 (via the Lathrop line).
After Pendergast pled guilty to income tax evasion charges in 1939, Gage, a Democrat, campaigned for mayor for the Citizens Association party consisting of both Democrats and Republicans. A signature aspect of the campaign was an appeal to housewives with the slogan:
Wanted: 75,000 women with pioneer courage...let us keep faith with those who blazed the trail.
He was to cut the city budget by $700,000, hired city manager L.P. Cookingham, and began to expand the city limits. He was elected three times. He was died after being hit by a truck while walking to work at 11th and Grand Avenue.
(We could not find a photo of John Gage. Do you have one?)