Born in Russia in 1839 to a Russian mother and British father, Mears was orphaned at two. Soon thereafter he was sent to San Francisco to live with relatives. With the outbreak of the Civil War, Mears enlisted in the California Volunteer Infantry. Mears' unit saw combat in the southwest, and at the end of the war he was discharged in Las Cruces in the Territory of New Mexico. After his discharge Mears traveled up the Rio Grande River into Colorado, eventually settling in the town of Conejos running a general store and later farming wheat in the San Luis Valley. Mears soon became aware of the difficulties involved in transporting goods over the high mountain passes of Colorado, and after encountering difficulty in transporting a shipment of wheat to the booming mining camp of Oro City he became involved in improving the narrow road over Poncha Pass. Mears applied for a charter to open a toll road over the Pass, eventually selling its rights to the Denver and Rio Grande Railway. Mears soon became involved in too road construction full time, developing a road into Lake City as well as a road over Marshall Pass. In 1883, Mears developed one of his most famous toll roads from the town of Ouray up the Uncompahgre Gorge into Ironton, Colorado. Besides toll roads, Mears was heavily involved in the establishment of railroads within Colorado, helping to develop the Rio Grande Southern and the Silverton Northern, as well as a number of narrow gauge lines. He dabbled in politics as well, serving as one of Colorado's three presidential electors supporting Rutherford B. Hayes in the 1876 election, and serving in the Colorado State Legislature during the 1880s. The Panic of 1893 hit Mears' investments hard, and he eventually lost control of his railroad holdings. By the turn of the century Mears had left Colorado and moved east, where he again was involved in establishing a number of roads and railroad lines, including the Chesapeake Beach Railway. Mears moved to California in his later years, and died in Pasadena in 1931.