In 1916, ITIO's contract was canceled with the introduction of general leasing, forcing the company to expand operations into other parts of Oklahoma. After discovering oil in Oklahoma City, ITIO sparked a significant oil boom in 1928.
On February 3, 1930, Henry V. Foster, son of Edwin Foster and sole owner of ITIO stock, sold 90% of the company to Cities Service. By 1940, ITIO had ceased operations, bringing an end to its remarkable chapter in oil history.