A description of the mining districts quoted from "The Mining Districts of Boulder County Colorado" by Percy S. Fritz:
ALLEN'S PARK MINING DISTRICT - "...lies just north of the present resort of that name contains only thirty-five patented mining claims. The only noteworthy thing in regard to them is the fact that they were all discovered and located in the decade following 1902."
BOULDER MINING DISTRICT - Organized pre-July 30, 1859. "... located near the junction of Fourmile (aka Four Mile) Creek and Boulder Creek. Although this is one of the smallest districts, it is one of the oldest. It was used to define part of the boundary of the Gold Hill district in July 1859, and also marked the east boundary of the Sugar Loaf district in November 1860. There are only twenty-three patented claims recorded in the district, the first two were placer claims located in 1873 while the last claim, also a placer, was located in 1903."
CENTRAL MINING DISTRICT - Organized September 7, 1866. "... lies in the vicinity of James Creek particularly around Jamestown which is the chief mining camp and trading point, but it extends as far north as the Middle St. Vrain Creek. The district was formally organized September 7, 1866. In 1930 there were 424 patented claims in the district."
GOLD HILL MINING DISTRICT- Organized circa March 7, 1859. "... lies approximately between Left Hand and Fourmile (aka Four Mile) creeks. It embraces all of that very rich district surrounding Gold Hill and Sunshine. Organized as Mountain District No. 1, Nebraska Territory, it is the oldest of the districts. In 1930 there were 577 patented claims in the district." [Includes much of Four Mile Canyon on the north side of the creek, and above the Boulder Mining District.]
GOLD LAKE MINING DISTRICT - Organized pre-February 26, 1861. This district probably dissolved in 1866 to become part of the Central Mining District which was organized on September 7, 1866.
GRAND ISLAND MINING DISTRICT - Organized March 16, 1861. "... in the southwestern corner of Boulder County, comprises a strip about four miles wide from the neighborhood of Castle Rock in Boulder Canyon, west to the Continental Divide. From its organization March 16, 1861, many claims were discovered and recorded, but the first patented claim, the Caribou (Survey No. 37), was not discovered until 1869. From the point of view of the number of patented claims this is the largest of the mining districts in the county. There were in 1930, a total of 866 patented claims in this district." [Includes the mines around Nederland, Eldora, and Caribou.]
MAGNOLIA MINING DISTRICT - "...located around the town of Magnolia was not discovered until 1875, it has been an active district ever since... 155 patented claims."
SNOWY RANGE MINING DISTRICT - Organized June 17, 1861. "... lying at timber line north of Silver Lake, has long been known. It was first organized July 17, 1861. There are only fourteen patented lodes in the district." (It was sometimes referred to in the newspapers as the Albion Mining District after the mining camp of Albion.)
SUGAR LOAF MINING DISTRICT - Organized November 9, 1860. "Around the base of Sugar Loaf Mountain lies the mining district of that name. First organized on November 9, 1860, it is now the second largest district in the county. There were 673 patented claims in this district in 1930." [Extends down into Four Mile Canyon on the south side of the creek.]
UTILLA MINING DISTRICT - Organized pre-September 7, 1861 near the small farming community of Utilla in Left Hand Canyon near Gold Hill. The Boulder lode was the first one recorded in this district.
WARD MINING DISTRICT - Organized September 12, 1860. "In a two mile radius around the town of Ward are 450 patented claims."
