   the denver & rio grande western railroad , often shortened to rio grande or d&rgw, formerly the denver & rio grande railroad, was an american class i railroad company. the railroad started as a  narrow gauge line running south from denver, colorado in 1870. it served mainly as a transcontinental bridge line between denver, and salt lake city, utah. the rio grande was also a major origin of coal and mineral traffic. in 1988, the rio grande's parent corporation, rio grande industries, purchased southern pacific transportation company, and as the result of a merger, the larger southern pacific railroad name was chosen for identity. today, most former d&rgw main lines are owned and operated by the union pacific railroad; several branch lines are now operated as heritage railways by various companies. the rio grande was the epitome of mountain railroading, with a motto of through the rockies, not around them and later main line through the rockies, both referring to the rocky mountains. the d&rgw operated the highest mainline rail line in the united states, over the  tennessee pass in colorado, and the famed routes through the moffat tunnel and the royal gorge. at its height, around 1890, the d&rg had the largest operating narrow gauge railroad network in north america. known for its independence, the d&rgw operated the last private intercity passenger train in the united states, the rio grande zephyr. at the end of 1970 it operated  of road on  of track; that year it carried 7733 ton-miles of revenue freight and 21 million passenger-miles. == history ==  frame|d&rgw logo used 1908â1921 === overview === the denver & rio grande 
3_ft_gauge_railways_in_the_United_States Companies_based_in_Denver,_Colorado Defunct_Colorado_railroads Defunct_New_Mexico_railroads Defunct_Utah_railroads Denver_and_Rio_Grande_Western_Railroad Former_Class_I_railroads_in_the_United_States Narrow_gauge_railroads_in_Colorado Narrow_gauge_railroads_in_New_Mexico Narrow_gauge_railroads_in_Utah Predecessors_of_the_Southern_Pacific_Transportation_Company Railway_companies_disestablished_in_1988 Railway_companies_established_in_1920