The Star-Spangled Banner proclaims that the US is "land of the free and home of the brave" and it is a motto that is carried throughout the country.

From the metropolis of New York City and Los Angeles to the sparse mountains of Montana and Wyoming, the US is a sprawling and diverse land. The same could be said about the evolution of its train network. Once huge steam trains would travel from Atlantic to Pacific transporting passengers and freight to every corner of the country. Now it's the Amtrak which dominates the rails.

While their day may be over, the US did create some of the most magnificent steam engines the world has ever seen. These behemoths of the track played a major role in the development of the country transporting vital resources to sparsely populated parts and serving the main cities.

Here are a selection of some of those majestic beasts.

Union Pacific Big Boy

Built in 1941, the Big Boy (as its name suggests) was an absolute giant of the rails. A total of 25 Big Boys were constructed in total and were the only locomotive to have the 4-8-8-4 wheel arrangement. They were put to use transporting coal from Wyoming to parts of California and other states.

They were called upon during the Second World War with resources needing to be taken to key ports on the US coast. The Big Boy 4005 was also used as part of an experiment which saw it converted to burn oil instead of coal, it was unsuccessful.

A number of Big Boys are on display today in various heritage parks across the US.

Southern Pacific 2472

The Southern Pacific 2472 was first introduced in 1921 being put to work on the Union Pacific Overland Route. This passenger service transported commuters from Ogden, Utah to Oakland, California.

Along with its sister locomotive the 2472 was replaced by the 4-8-2 Mountain type engines and was then tasked with running the Sacramento-Oakland passenger train and then moving on to the San Francisco-San Jose, California line.

The trains were retired in 1957 however thanks to significant restoration it is still operational on the heritage Niles Canyon Railway in Alameda County, California.

Union Pacific Challenger

The Union Pacific Challengers were one of the most prominent sights on the rails across the US during the early parts of the 20th century. The company made 105 of these 122 feet long trains which patrolled pretty much all Union Pacific routes.

Challengers were used mainly for freight deliveries but a select few ran passenger services through mountain territory to California and Oregon. The name Challenger was given to all locomotives which carried the 4-6-6-4 wheel arrangement.

Today only two of the Challengers remain with the Union Pacific 3985 being used for excursions and the Union Pacific 3977 which is on display in North Platte, Nebraska.

Southern Pacific GS-4

The Southern Pacific GS-4 was a much more streamlined locomotive than many others around at the time. Built in 1941 the engine had a 4-8-4 wheel configuration and was used on the Southern Pacific Company routes.

It was predominantly a passenger train, the GS-3s were geared more towards freight, and had the capability of reaching speeds of 110 mph. It ran numerous routes across California such as the Coast Daylight, San Joaquin Daylight, Cascade and Golden State.

The trains was officially retired in 1958 but has since been restored and now sits at the Oregon Rail Heritage Center.