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Survey of Historic Sites and Buildings

	UNITED STATES ASSAY OFFICE Idaho
Location: Ada County, 210 Main Street, Boise. Idaho State Historical Society

Ownership and Administration. U.S. Government; Department of Agriculture Forest Service.

Significance. The discovery of gold on the Clearwater River in 1860 brought the usual rush of miners, and 2 years later prospectors found new placers on the Salmon River and in the Boise Basin. These activities soon led, in March of 1863, to the creation of Idaho Territory. Between 1861 and 1866 the Territory's gold output totaled about $52 million, or about 19 percent of the Nation's total, but shipping costs to the U.S. Mint at San Francisco were high. For these reasons a strong demand arose for a Federal mint or assay office in Idaho. In 1869 Congress responded by appropriating $75,000 to erect a building for a Federal assay office in Boise.

A. B. Mullett, Supervising Architect of the Treasury Department, directed the preparation of plans and specifications. Construction began in July 1870 and required about a year. The building was of dignified design and measured 48 by 46 feet. It had a basement and two stories, and its exterior native sandstone walls were more than 2 feet thick. The coursed stone face was marked by ashlar corner quoins. The architectural style is difficult to classify, but has been described variously as "Italian Villa," "French Chateau," and "provincial." The building cost a total of $77,252. A delay in the receipt of machinery prevented the first assay from being made until March 2, 1872.

By the time the assay office began to function, the rich surface placers of gold in Idaho had been almost depleted and production underwent a considerable slump until 1883, when miners opened the Coeur d'Alene region. They sank deep shafts, built stamp mills, and opened new mines, including silver and lead mines. By 1895 annual deposits in the assay office had reached more than a million dollars. For the next 11 years they averaged a million and a half dollars. By 1917 the Idaho mines had yielded $400 million—one-fourth in gold, one-fourth in silver, and one-half in lead. The assay office continued operating until 1933, when the U.S. Forest Service acquired the building as headquarters for the Boise National Forest and remodeled it.

Present Appearance. Originally the offices and assayer's laboratory were located on the first floor. The second floor contained the living quarters of the chief assayer. Despite slight alterations to the exterior and interior during the remodeling in 1933, the basic structure and general appearance are essentially the same as those of the original building. [16]

NHL Designation: 05/30/61