Tom was a silver miner at Kokomo, Summit County, Colorado in 1875. He paid for his youngest brother, Dr. John Gilligan, to join him in Kokomo in 1878. The post office opened May 5, 1879. Kokomo became a town on June 3, 1879 with a population of 1500. The 1879 Kokomo Business Directory lists Thomas Gilligan under Cigars & Tobacco, and Club Rooms. Dr. John found the wild life of the western mining camp to be bloody, so he soon left to get an MD degree at the American Medical College in St. Louis, MO (1882). At its height in 1881, the population of Kokomo was 10,000. There were 12 hotels, 5 general stores, 20 saloons, 4 dance halls, several brothels, 1 newspaper, and many other businesses. Tom got in a fight on July 19, 1881 (nobody died). Five months later, he sold his property and saloon (Georgetown Headquarters) on Ten Mile Avenue to Dr. John, then returned to Ireland. A fire destroyed the town that winter. When the community was rebuilt, most of the homes were built in the twin town, Recen, which was renamed Kokomo. Kokomo struggled and ceased to exist after 1971, when Climax (once the world's biggest molybdenum mine) purchased the land for tailings ponds (waste after ore is taken).