STRASBURG, Colo. Union Pacific's iconic Big Boy No. 4014 steam engine will conclude its Heartland of America Tour with two Colorado stops. Big Boy will chug through Strasburg between 3:45 p.m. and 4:15 p.m. on Oct. 21 at the Monroe Street Crossing. It will then move through Greeley between 12:35 p.m. and 1:05 p.m. on Oct. 23 at the 10th Street Crossing. According to Union Pacific, 25 Big Boys were built in the 1940s to conquer Utah's Wasatch Mountain Range during World War II and typically operated between Ogden, Utah, and Cheyenne, Wyoming. The first Big Boy was delivered in 1941.Big Boy No. 4014 was delivered to Union Pacific in December 1941. The locomotive was retired in December 1961 following 20 years of service and 1,031,205 miles of travel, according to Union Pacific. It was reacquired from the RailGiants Museum in Pomona, California, in 2013 and relocated back to Cheyenne.After a multi-year restoration project, Big Boy No. 4014 returned to service in May 2019 to celebrate the 150th anniversary of the Transcontinental Railroad's completion. Visitors looking to see Big Boy No. 4014 must remain 25 feet back from the tracks at all times, according to Union Pacific safety protocols. Train enthusiasts can follow Big Boy's journey on social media.