A train was a grouping of vehicles that moved over two rails, transporting passengers or freight. Trains were widely used on Earth during the 19th, 20th, and 21st centuries. Trains consisted of a locomotive, which provided the power for trains to move, which was attached to one or more vehicles designed to either carry freight or passengers.
As railroads expanded across the United States in the 19th century, railroad towns sprouted up. Some were abandoned after construction of the rail lines ended. (TNG - Maximum Warp novel: Forever Dark)
During the 19th and 20th century, the Orient Express ran from Paris, France to Istanbul, Turkey. The Orient Express became associated with intrigue and luxury travel. Dr. Beverly Crusher became fascinated with the experience of traveling on the train, and had a holodeck program that recreated the early Orient Express. (TNG episode: "Emergence")
In 1930 in a timeline created when Leonard McCoy saved the life of Edith Keeler, McCoy watched the trains while in Brooklyn. After waiting one year for a rescue, Keeler suggested that McCoy take a train back to Atlanta. In 1932, he boarded a train to Philadelphia. When he ran out of money he hitched rides on empty cars, eventually jumping off near Hayden, South Carolina. (TOS - Crucible novel: Provenance of Shadows)
The popularity of using trains for transporting passengers declined during the 20th and 21st centuries as other means of transportation — such as automobiles and air travel — became more popular. Despite this, some humans continued to prefer trains. Zefram Cochrane did not like flying, and preferred trains when traveling. (TNG movie: Star Trek: First Contact)
- Baltimore freight yard (Maryland, Earth, 20th century)
- Grand Central Station (New York City, Earth, 20th century)
- Pioneer Railroad (United States, Earth)
- Railroad Building (Flushing Meadows, Earth)
- Southern Pacific Railroad (San Francisco, Earth)
- TOS - Crucible novel: Provenance of Shadows
- TOS comic: "Husian Gambit"
- TOS - Klingons: Blood Will Tell comic: "Losses"
- TNG episode: "Emergence"
- TNG movie: Star Trek: First Contact
- TOS novel: How Much for Just the Planet?
- TOS novel: Ishmael
- TOS novel: Spock's World
- TOS novel: Burning Dreams
- TOS novel: Best Destiny
- TNG novel: The Best and the Brightest
- DS9 novelization: Far Beyond the Stars
- DS9 novelization: Trials and Tribble-ations
- SNW short story: "Shanghaied"
- TLE novel: Deny Thy Father