A few years after the construction of the first engines, the design of the Shay locomotives changed from the vertical boiler to a classic, horizontal boiler barrel with clearly visible steam and sand domes. One of these nine-ton-class models was procured by the Gilpin Tramway in 1887 for its 15.5-mile route in Gilpin County near Denver, with a two-foot gauge. It had the factory number 181 and was given the number 1 and the name “Gilpin” by its owner. Four more Shays followed in the years up to 1902 with 12, 15, 17 and 18 tons. The first two were sold in 1905, the others remained in service until the line was closed in 1917.

After the KCS had been a friend of Mallets for a long time, they procured a total of ten locomotives with the wheel arrangement 2-10-4 in 1937. Five each were coal and oil fired. This was the first time a boiler of this size has been used with a boiler pressure of 310 psi or 21.4 bars. They achieved an indicated power of 4,825 hp and minus the mass of the locomotive and tender there was still 4,475 hp left at the draw bar. During the Second World War, they were also used to transport troops, and with their 70-inch driving wheels they were able to keep to the timetables of passenger trains. They were replaced by diesel locomotives in 1952 and 1953 and scrapped in 1954.

The Manitou & Pikes Peak Cog Railway, opened in 1891, provides an access to the famous mountain in Colorado. It starts in Manitou Springs at an elevation of 6,320 ft (1,930 m) and reaches the top at 14,115 ft (4,302 m). While its steepest section has a gradient of 25 percent, the average is twelve percent. All of its steam locomotives were built by Baldwin, with No. 6 being delivered in 1906.

No. 6 was the first one to be fired with oil. After its older sisters were rebuilt as four-cylinder Vauclain compounds, it was built this way and had its axles turned by levers instead of direct connecting rods. The boiler and the cab were inclined by 16 percent to compensate for the gradient. As opposed to most of its sisters, it is not preserved today since it was scrapped in 1955.

In 1913 and 1914, the MKT received 60 Mikados from ALCO-Brooks with Walschaerts valve gear, which were listed as class L-1a. Their Number was augmented in 1914 by ten more, which received Baker valve gear and were listed as Class L-1b because of this difference. They were initially coal fired but underwent a conversion to oil firing by 1922. The new tenders now held 2,990 gallons of oil instead of 14 short tons of coal and had a slightly smaller water reserve. The boiler pressure had meanwhile been increased from 185 to 195 psi. 

The 55-mile-long San Joaquin & Eastern was built in Fresno County, California in 1912 to serve the Big Creek hydroelectric dam site. Since it was sometimes described as the most crooked railway line in the world, steam locomotives with bogies were used on the mountainous sections. After five Shays from 1912, six more Climax were purchased between 1916 and 1923.

The first five of these were of the three-truck C class with 70 tons. Like many railroads in the region, they were fired by oil. When the unprofitable line closed in 1933, No. 108 shown was shipped overseas. The sixth Climax with number 110 from 1923 was of the B class with 45 tons.

The Union Railroad was part of US Steel and was responsible for freight traffic between some of their plants and the main lines of several railroads in western Pennsylvania. The low speeds made it possible to achieve the largest possible adhesive weight without using a leading axle and without exceeding the length of the existing turntables. There was an additional booster on the first tender axle.

Since these locomotives were the only ones in North America with the 0-10-2 wheel arrangement, the name “Union” came about. The service at the Union Railroad ended in 1949 with the purchase of the first diesel locomotives. Nine of the ten locomotives were sold to the Duluth, Missabe and Iron Range, which also belonged to US Steel. They retired from service there between 1958 and 1961 and DM&IR number 604 is now on display in Greenville, Pennsylvania.

The Uintah Railway operated a three-foot gauge line in Colorado and Utah where it hauled asphaltite over Baxter pass. This not only had tight curves, but also a six mile long 7.5 percent ascent followed by a seven mile long 5 percent descent. Even though they had used Shays, many trains could only be handled by two of those. To remedy this problem, they ordered a powerful articulated 2-6-6-2T tank locomotive from Baldwin in 1926.

This one now could haul the same load as two Shays. This meant a maximum trailing load of 240 tons at 5 percent and 145 tons at 7.5 percent. Due to problems getting dry steam on severe grades, it was retrofitted with a second steam dome in front of the cab. After this, a second locomotive was ordered in 1928.

The end of the Uintah Railway came in 1939 when trucks had taken over their tasks. Both No. 50 and 51 were sold to the Sumpter Valley Railroad in Oregon. There they were rebuilt to oil-burning tender locomotives and renumbered to 250 and 251. After operating there until 1947, they were sold to the International Railways of Central America in Guatemala, where they were retired in 1962 and 1964.