In 1826, the Mohwak & Hudson Railroad was founded to construct a rail line between Schenectady and Albany as a faster alternative to compete with the Erie Canal. For the route to be opened in 1831, a locomotive was manufactured at the West Point Foundry, which should take over the operation with passenger cars converted from horse carriages. As an affront to Governor DeWitt Clinton, who was always on the side of the canal, the locomotive was named after him.

In contrast to the Grasshoppers built at the same time, the “DeWitt Clinton” already had a horizontal boiler barrel, a steam dome and a smokebox with a chimney at the front end of the boiler. It also already had an attached tender for storing supplies.

With the coal from the Lackawanna area originally used in the first test runs, no sufficient range could be achieved, and so the coal was soon replaced by coke. Using the new fuel, the 16-mile distance was covered at an average of between 25 and 27 mph. Up to 18 passengers could be transported in each of the three cars.

The original locomotive was scrapped after only two years of service and replaced with newer models. Nevertheless, it laid the foundation for the fact that the canal lost importance from the 1860s. In 1893, the New York Central as the successor to the Mohawk & Hudson made a working replica, which was shown at the Chicago World's Fair that same year. It was in regular service into the 1950s and has since been in the Henry Ford Museum in Dearborn, Michigan.

Most of the New York Central class H-5 Mikados came from the rebuilds of a total of 482 G-5 class Consolidations. Not only were locomotives rebuilt directly by the New York Central, but also by its subsidiaries Boston & Albany and Big Four. The firebox remained largely unchanged and the boiler barrel was lengthened. While the cylinders were enlarged, the boiler pressure was reduced by 20 psi. The combination of these measures allowed to increase speed. Overall, the adhesive weight also increased. After the G-5 had already been built in different versions, there were also many differences within the H-5 class. In addition to the rebuilt locomotives, 179 were newly built.

After the K-2 class Pacifics, which did not have a superheater from the factory, the New York Central had a larger number of superheated K-3 built between 1911 and 1925. Their task was to pull the heaviest express trains. Numerous series from the K-3a to the K-3r were produced, with the latter being built for the Big Four. The different series were almost identical in the basic dimensions, but there were differences in the boiler. Some of the locomotives had a booster on the trailing axle. 

The K-5 class designated the heaviest Pacifics of the New York Central System. Built primarily for the subsidiaries, they were divided into the K-5 and K-5a subclasses. Numbers 4915 and 4917 were fitted with streamlining in 1936 designed by Henry Dreyfuss and called the “upside down bathtub”. These two pulled important express trains like the “Mercury” and became subclass K-5b.

After the 185 “Mohawks” of the L-1 class, the New York Central developed the more powerful L-2 class. It was also intended purely for freight service, but had a larger boiler, a feedwater heater and a booster on the trailing axle. The driver diameter remained at 69 inches or 1,753 mm and allowed a maximum permitted speed of 60 mph or 97 km/h.

Production began in 1925 at ALCO in Schenectady with 100 locomotives of the subclass L-2a. Further subclasses up to the L-2d all also came from Schenectady and brought the number to a total of 300 by 1930. They differed in the boiler dimensions, wheelbases and the feedwater heater used, which could be of the Elasco, Worthington or Coffin types.

In 1939, two L-2d were converted as prototypes for the L-3 for mixed service. These were intended to achieve higher speeds without requiring larger drivers. Thanks to roller bearings on the axles, cylinders with a smaller diameter and a higher boiler pressure, they could be approved for speeds of 80 mph. 

The third of NYC's four classes of 4-8-2s, called “Mohawks” there, was the L-3. In contrast to its predecessors, it was not only intended to pull freight trains, but also passenger trains. An L-2d had already been modified accordingly for testing. The driver diameter was left at 69 inches and the decision was made not to use a second trailing axle in view of the existing infrastructure.

The differences between the L-3 and the L-2 included higher boiler pressure, smaller cylinders and several improvements to the running gear. In the case of the running gear, this included improving the counterbalancing, designing many rotating parts in lightweight construction and mounting the axles in roller bearings. The L-3b and c subclasses were equipped with a booster on the trailing axle. 

Of a total of 65 locomotives, 35 were actually built for mixed traffic and 30 only for freight traffic, which only had plain bearings on the driving axles. The large six-axle tenders had an exceptionally large coal capacity of 43 short tons. The water capacity, on the other hand, was relatively moderate at 15,500 gallons, but the New York Central had water troughs for refilling while running. In this way, large distances could be covered without stopping.

With the driver diameter of 69 inches, speeds of more than 80 mph could be achieved. However, the wheelbase was chosen in such a way that wheels of up to 72 inches could also be fitted. This was only applied to number 3000, which served as a prototype for the L-4.

Based on the success of the L-3 Mohawks, the New York Central designed a faster variant that was designated L-4. It had the same boiler, but drivers which were 72 instead of 69 inches and cylinders with a diameter that was half an inch greater. They now also got roller bearings on the drivers. Despite their higher top speed, they were also used for both passenger and freight trains.

In 1942 and 1943, two batches of 25 each were built as L-4a and L-4b. A tender with a coal capacity of 42.5 tons was enough to cover half the distance from New York City to Chicago without refueling. The 15,500 gallons of water were replenished at track pans while running. The tender of the L-4b was only minimally smaller. They were retired between 1954 and 1957.

After the first class U-1 switching locomotives with a 0-8-0 wheel arrangement, which were only built in small numbers, New York Central procured a larger number of class U-2 locomotives. These were slightly lighter than their predecessors and only had a cylinder diameter of 23.5 instead of 25 inches with the same wheel diameter. 

From 1916 a total of twelve series were created, which differed slightly primarily in the boiler dimensions and were given the letters from a to l. The first series of the U-2a was delivered by ALCO-Brooks and the last series of the U-2l by ALCO-Schenectady. The remaining series came mainly from Lima, only the U-2d came from ALCO-Pittsburgh. The U-2i to U-2l were only delivered to subsidiaries of New York Central, more specifically to Chicago River & Indiana and Boston & Albany.

Although the last series of U-2s had not been built for the subsidiaries until 1923 and 1924, New York Central procured new class U-3 switchers as early as 1918, which corresponded to the standard USRA 0-8-0 design. Despite this, the U-2 class engines survived into the 1950s.

Of a total of 1,350 Mikados owned by the New York Central, the H-10 was the last and by far most modern. It started in 1922 when William E. Woodard of Lima was tasked to design a modern freight locomotive that was much more efficient than existing types. This one went to NYC's subsidiary Michigan Central and was numbered 8000.

It was based on the H-7e, but the most significant change was the superheater area that had nearly been doubled in comparison to other Mikados. To achieve this, the boiler only had flues with superheater elements inside them and no tubes at all. Additionally, it had a feedwater heater, improved draughting and streamlined steam passages. To improve the response to throttle inputs, it also got a front end throttle. Like the majority of NYC Mikados, it also had a trailing truck booster. 

In the result, the H-10 was 26 percent more efficient than the H-7. During its test runs, the 8000 managed to haul a train of 10,039 tons over nearly 50 miles. Due to its great success, it formed the base of 301 more H-10a and H-10b locomotives built by Lima and ALCO for the NYC and its subsidiaries. Many consider them the prototypes of Lima's superpower design and they didn't need many modifications during their service life. They were scrapped between 1950 and 1954.

The New York Central operated a number of major express trains from New York City, which ran at high speeds mostly in the lowlands and enjoyed increasing popularity. These were primarily the “20th Century Limited” to Chicago and the “Empire State Express” to Detroit. Since the existing Pacific locomotives had reached their limits in the mid-1920s, the task was to develop a new locomotive with a larger boiler. This should also be able to pull 16 or 18 cars instead of the previous twelve. Since there were hardly any inclines on the affected routes, three coupled axles were sufficient.

With the “Superpower” locomotives with the wheel arrangement 2-8-4 (Berkshire), it had already been confirmed that a significantly larger firebox could be installed with a second trailing axle, which enabled a significantly higher boiler output. So the Pacific was expanded with the second trailing axle and thus the first steam locomotive in North America with the wheel arrangement 4-6-4 was created. Although the Milwaukee Road had already developed a comparable locomotive shortly before and wanted to name the wheel arrangement as “Baltic”, the designs were actually implemented later. Thus, the New York Central was able to designate the new wheel arrangement and named it “Hudson”, after the river they were supposed to travel along.

For starting, all Hudsons from the first series received a booster on the second axle of the rear bogie. Despite this, they were said to have performed relatively poorly at low speeds, but developed well over 4,000 hp at high speeds. Officially, they were designed for a top speed of 110 mph. However, according to unofficial information, they are said to have reached speeds of at least 123 mph when driving in delays. The standard performance for the J-1 was 1,270 short tons at an average speed of 55 mph. 

There were 205 examples of the J-1 in five series, which were designated as J-1a to J-1e. A total of 60 examples of these went to other Big Four affiliates. This were 30 for the Michigan Central and 30 for the Cleveland, Cincinnati, Chicago & St. Louis. From 1928 the J-2 was built in parallel, which went directly back to an order from Boston & Albany and was built 20 times just for them. It had slightly smaller coupling wheels and a Coffin type feedwater heater.

In 1934, the last J-1e built received an Art Deco streamlined fairing designed by Carl F. Kantola. The aim was to emulate the diesel-powered streamlined trains that were just emerging at the time. Ten of 50 examples of the J-3a built from 1937 received factory streamlined fairing designed by Henry Dreyfuss. The J-3a otherwise differed from the J-1 by having a smaller superheater and a boiler pressure of 275 psi. However, this was later reduced to 265 psi. 

The J-3a in particular was characterized by the fact that it was extremely low-maintenance and could cover long distances non-stop. The interval between two major repairs was between 185,000 and 200,000 miles, which corresponded to around two years of service. Additionally, it used seven-axle tenders with a laden weight of more than 400.000 pounds, which could cover long distances before having to refill water and coal. The last Hudsons served until 1957, when New York Central's conversion to diesel traction was complete. Thus they lived even longer than the even more powerful Niagaras built after them. Unfortunately, they met the same fate as many other US steam locomotives, so that despite their historical significance, they were all scrapped.