Placer gold discovery in 1866 near present-day Leesburg, and the resultant gold rush, led to lode gold discoveries in the surrounding area (Oberbillig, 1960). Gold was reportedly first discovered on the UP & Burlington property in 1882 (Brewer, 2012). Two claims, the UP and the Burlington, were patented in 1900 and most of the development work was done prior to 1907. Development included six tunnels, distributed up the mountain side at elevations 100 feet apart, and a shallow shaft beyond the upper tunnel (Umpleby, 1913). A total of 2745 feet of workings included 2342 feet of drifts, 385 feet of raises, and 18 feet of shaft. A 10 stamp mill was constructed in 1907 and was operated intermittently remnants of the mill exist today. The Number 5 tunnel (second lowest) was opened and sampled in 1934 and an ore reserve calculation report, computed from map records, was prepared in 1935 (Guewilik, 1935). Two of the historic portals (No. 5 and No. 6, the two lowest portals) were exposed in the summer of 2011 by the UP & Burlington Development LLC.