This post card shows a diesel engine in the livery of the Denver & Rio Grande Western Railroad. It is heading west, after having passed under the Continental Divide through the Moffat Tunnel.
This view - with the arrow to help you to see - shows the entrance to the tunnel.
Almost all of the information below came from the Wikipedia website:
David Moffat was born in Washingtonville, New York on July 22, 1839. He moved to Denver, Colorado in 1860. On April 17, 1865 the First National Bank of Denver, was organized. It had little success until 1867, when Moffat was elected cashier. He remained the controlling mind in the institution until his death, being elected to the presidency in 1880. He instituted polices and methods which led to the growth and success of the bank for years to come. But, Mr. Moffat was more than a banker. He was a railroad visionary.
Unfortunately, as the Union Pacific Railroad built the transcontinental railroad heading west it by-passed Denver for a much flatter and easier to construct route. Building the transcontinental railroad through Nebraska, totally by-passing Colorado, left the Denver stranded from the commerce connections that it had hoped for.
As a result of this snub, the governor of Colorado, together with other local business leaders, including David Moffat partnered with East Coast investors to form a railroad company (the Denver Pacific Railway) that would link Denver and the Colorado Territory with the transcontinental railroad. The plan was to link Denver with the Union Pacific at Cheyenne, Wyoming. The company was incorporated on November 19, 1867 as the "Denver Pacific Railway and Telegraph Company". They broke ground on May 18, 1868 and two years later the line was completed. This was the first railroad company with which Mr. Moffat was involved.
The second railroad company, the Denver, South Park and Pacific Railroad, with which Moffat was involved got its start intending to connect the mining area of Colorado to the city of Denver. It began in 1872 and operated as an independent railroad until it was sold in foreclosure proceedings in 1889.
Looking south, Mr. Moffat, along with other business men, began the Denver and New Orleans Railroad. Their intention was to bring business to and from the Gulf of Mexico. Their company was later known as the Denver, Texas & Gulf Railroad and would become part of the Colorado and Southern Railway. They built from Denver to Pueblo, Colorado. Then General Grenville Mellen Dodge led the team that completed the line to Fort Worth. General Dodge took over the building of the Union Pacific Railroad in 1866. Having been a commander of the Union forces in the Civil War, he was able to exercise his leadership and get the track building back on track.
As if that wasn’t enough railroading, David Moffat then started the first trolley line in Denver. He and other associates (including the Governor of Colorado again) started the Denver Tramway. The tramway made use of a variety of types of streetcars, including conduit cars (until 1888), cable cars (until 1900), and trolley cars (until 1950). At the height of its trolley operations, the tramway owned 160+ miles of track and operated over 250 streetcars.
His next venture was to be the Manitou and Pike's Peak Railway climbing to the top of Pikes Peak. The base station is in Manitou Springs, Colorado. The railway is the highest in North America by a considerable margin. It was built and is operated solely for the tourist trade. The railway was started by Zalmon G. Simmons, inventor and founder of the Simmons Beautyrest Mattress Company and David Moffat. The company was founded in 1889 and limited service to the Halfway House Hotel was started in 1890. The summit was reached the following year.
In 1885 David Moffat was elected to Denver & Rio Grande board. Then in 1887 Moffat was elected president of the Denver & Rio Grande. Moffat built the Glenwood to Grand Junction, standard gauging Pueblo to Grand Junction, and the Tennessee pass tunnel.
1892 David Moffat next developed a railroad to Creede from Wagon Wheel Gap, Colorado. It ran along the banks of the Rio Grande to Creede, which was then a booming silver camp, at which he owned several mining clams. The Denver & Rio Grande Railroad wanted nothing to do with it, so Mr. Moffat built the road entirely at his own expense. He formed the Rio Grande Gunnison Railway Company. Then when it began to make a profit he sold it at a heavy profit to the Denver & Rio Grande Railroad.
Finally, David H. Moffat and his business associates established the Denver, Northwestern and Pacific Railway. It originated in Denver and was planned to terminate in Salt Lake City, Utah, though it went bankrupt before reaching that city. By 1913, it was reorganized as the Denver & Salt Lake Railway. It was along this railway that the Moffat Tunnel was bored. David Moffat envisioned a tunnel through the continental divide west of Denver. Construction of the Moffat Tunnel took place from 1923 to 1927. It was officially opened on February 28, 1928 with much fanfare and several trainloads of special guests in attendance at the East Portal, the picture on this post card. Denver & Salt Lake Railroad locomotive 205, a 2-6-6-0 compound locomotive, pulled the first official passenger train through the new tunnel. The Moffat Tunnel is 6.2 miles long and is the 6th largest tunnel on earth.
Mr. Moffat died on March 18, 1911, before he could realize this dream.
I believe that it was printed by the Curt Teich company. The block where the stamp is to be placed has a very familiar looking pattern to the numbers.