Gibson was given a thorough education and graduated from Bowdoin College in 1851.
Gibson, at once, entered politics, being a member of the Maine legislature in 1854, but upon the death of his father took charge of the home farm.
In 1858, he went to Minneapolis, Minnesota, then a town of about 2, 000 people, where he built a flouring-mill, the first in the city. Then he started construction of the North Star Woolen Mills, whose product was soon widely known. Within a few years, he made a fortune but lost most of it in the panic of 1873.
In 1879, he moved to Fort Benton, Montana, and engaged in sheep-raising. Here again, he was a pioneer, for he was the first large band of sheep in northern Montana. In following, his sheep over the country he came upon the Great Falls of Missouri.
He said later that at that time he saw in them only beauty for he did not know the great possibilities of waterpower in developing electricity, but he soon formed a plan for an industrial city and sought the aid of James J. Hill who had recently acquired the St. Paul & Pacific Railroad.
Hill promised support, and Gibson began to acquire land on the site of his proposed city and to get title to the power sites and neighboring coal deposits. In 1887, the first trains were run into the new town.
Gibson, who served as its first mayor, planned the city on a large scale and with an elaborate park system, and forty years later, with a population of 35, 000, Great Falls, Montana, has felt no cramping and no need for revision of the original plans.
For the remainder of his life, Gibson was closely connected with the development of the waterpower, coal-mining, railroad-building, and sheep-growing of northern Montana.
In 1893, when a bill for providing for higher education was before the Senate he argued passionately but in vain for the consolidation of all branches of higher education into one university.
In 1901, he was elected United States senator to complete the term of William A. Clark who had resigned in 1900. His work in the Senate lasted only four years.
He did not formally retire from the control of his extensive business until he was eighty-five and took an active interest in the University of Montana until the time of his death.
Gibson was an influential member of the Democratic party but his political activities were rarely of a partisan character.
Gibson was a member of the convention that framed the constitution of Montana, and a member of the first state Senate ( 1891).
Gibson was married to Valeria Goodenow Sweat on August 23, 1858.