Seventh child of Daniel & Sarah Crawford Loomis, George's mother died when he was five years old. In 1798 he went to live with his sister Charlotte in Vermont. He had a fondess for horses and a predilection for collecting those that did not belong to him. He learned early that stolen horses could easily be driven to Connecticut and sold with no questions asked. Hewas suspected by the local sheriff and was given a warning. Unable to resist the temptation of stealing horses, he continued his pursuit. In 1802 he fled Randolph, Vermont just ahead of the Sherriff's posse and headed towards his sister Clarissa Loomis Preston's home in Sangerfield, Oneida County, New York, with over $3000 in gold coins in his saddlebags.

After looking to purchase land in the area with specific features, about 1806 he purchased fifteen acres of land on Swamp Road, four miles southwest of Sangerfield Center, near the Oneida-Madison county line. The western fringe of his land was the Nine-Mile Swamp. This land had a high pinnacle to use as a lookout and many areas in which to hide stolen horses. Over the years this small acreage was added to and eventually grew to over 400 acres.

In 1814 he married Rhoda Marie Mallett, dau of Zachariah and Abigail Osburn Mallett and they settled in a house built on the high ground of their property. They raised a family of twelve children, two dying young.

By 1850 the Loomis family was growing more powerful each day. The number of accomplices they had stealing for them was nearing 200, and their activities spread far from Sangerfield. Burglaries, petit larceny, grand larceny, robberies and horsethefts were rampart. Crawl spaces in the Loomis home and barns overflowed with stolen goods and the Nine Mile Swamp could not contain all the stolen horses.

With his death in 1851, leadership of the Loomis Gang was taken over by George 'Wash' Jr. and would continue for many years to come.

No tombstone marks the grave of George Washington Loomis.