The settlement of Radium, on the north bank of the Colorado River in Gore Canyon, was established in 1906, when railroad construction of the Denver and Salt Lake Railroad brought in foreign workers, typically Swedes, Greeks, and Italians. After the rail lines were built, livestock was shipped out and vegetables such as potatoes, peas, and lettuce were grown and picked at the last minute so they could be shipped while still fresh.

Originally the land was homesteaded by the Murgrage and Hoyt ranch families. Railroad passenger service during the winter months was scheduled only three times a week each way but even then, couldn’t always get through. Nonetheless, the “Try Weakly Railroad” service was better transportation than anything residents had ever had before.

The name of Radium was suggested by Harry S. Porter because of the radioactivity found in his mine. The nearby Radium Copper Mine was a large copper producer at one time.

Maintainance workers for Union Pacific, current owners of the railroad, are still based at Radium.

In 1938, Grand County decided to establish a library to act as a central reservoir of knowledge for its citizens. The community realized that few people can purchase all of the books and other materials which they may need, and so they agreed to pool their money in the library to build its central collection. At the same time they wanted to be sure that their interests would always be represented in the operations of the library, and so they formed a board of trustees from among themselves.

At about the same time, the federated women's clubs in Granby and Grand Lake, for the same reasons, set up lending libraries in those two communities. Run by the clubs for many years, both were eventually incorporated into the County Library. In 1994, the Committee to Protect the Library was established to petition the Board of Commissioners to increase funding for the library to set aside a completely separate library fund, which would be administered as a Library District. The voters approved the move on November 8, 1994, and Grand County Library District was formed on January 1, 1995. Today, the library still serves that same basic function for the community as well as new roles acquired in the intervening years.

On June 4^th, 2004 an armored D-9 Caterpillar was used by disgruntled Granby businessman Marv Heemeyer in a rampage that caused an estimated $5 million in damage and left part of the town of Granby in rubble. Heemeyer's slow-moving, 90 minute demolition, fueled by his anger at local officials and business owners who supported construction of a cement batch plant, left 13 buildings demolished or damaged and ended when he committed suicide inside the cab that he had welded shut. The buildings targeted included the town hall, the library, the electric company, a bank, the newspaper and the home of the former mayor. The town of Granby was spared any human injuries or loss because of the complete evacuation of the town through the reverse 911 system and many local law enforcement officers who went door to door to warn the townspeople. The town of Granby immediately launched fundraising efforts to offset the losses suffered by targeted businesses and citizens and the destroyed buildings were mostly rebuilt by the following year.

Kremmling started as a general mechandise store, owned by Rudolph (or Kare) Kremmling, on the ranch of Dr. Harris, located on the north bank of the Muddy River. In 1888, John and Aaron Kinsey had part of their ranch platted, calling the site Kinsey City. Kremmling moved his store across the river from the new site and the town that subsequently developed became known as Kremmling. There was a post office established at Kremmling as early as 1885 and the town was incorporated in 1904. 

The Middle Park Fair was established here in 1912. Famous Western Novelist Zane Grey spent time in Kremmling and, as a result, wrote "Mysterious Rider" in which the area is shown as a classic Western setting.

During World War II the town was the location of a prisoner of war camp where German prisoners cut ice that was shipped by rail to other locations.

The local ranching industry, the presence of the railroad and its strategic location at the confluence of the Colorado River, the Blue River, and Muddy Creek made Kremmling a natural location for a town, which still retains the “Old West“ atmosphere.