Montana created twenty-six counties during its 1910 county-splitting craze, including Big Horn County, formed from parts of Yellowstone and Rosebud Counties in 1913. Private entrepreneurs built the new county’s first courthouses, and after leasing offices in the Sullivan Block in 1913, the county in 1918 contracted with W. O. Lee to furnish 20 rooms for courthouse purposes. Lee hired Percy Wilcox to construct the $60,000 two-story building, whose geometric decoration, bands of windows, and horizontal emphasis likely reflected the Prairie style. Sibley Drug Store and Stockman Bank also occupied the business block, and the bank fitted its interior with mahogany wainscoting, marble trim, and a marble floor. In 1923, the bank failed during the agricultural depression, and the county moved its offices back to the Sullivan Block that same year. Later occupants included a post office, a clothing store, and a dance hall on the second floor in the former courtroom, and the Wilson Building sign dates from the 1960s or 1970s, when Judge Robert Wilson owned the property.