Once the railroad began, the first trains were horse drawn wagons. The distance
between Baltimore and Ellicott's Mills was too great for a single team of horses known as a relay. And so, a fresh team was acquired halfway between the 2 towns. As the B&O grew, Relay grew into a regular freight and passenger station. Construction of Relay Station began in July of 1872 and torn down in 1950.

The name "Relay" refers to the place where the horse team was changed halfway between Mt. Clare Station and Ellicott's Mills.

This area was chosen as the switching point for the new Baltimore to Washington branch of the B&O.

The one obstacle to this new line was the Patapsco river, which had to be bridged.

Benjamin Latrobe designed the bridge known as the Thomas Viaduct, and John McCartney was the builder.

The Thomas Viaduct was named for Plillip Thomas, first President of the Baltimore & Ohio Railroad. It was the bridge that if it could be built, would most likely collapse under it's own weight, or so people believed. Construction began on July 4 th, 1832 and was finished in 3 years, costing $ 142,236. The bridge consisted of 8 arches, was 60 feet tall, 26 feet wide and 612 feet long. Opening day was July 4 th, 1835. In 1964, the U.S. Dept. of the Interior named the viaduct a National Historic Landmark.

notes

During the Civil war, Maryland was mostly sympathetic to the southern cause. If Maryland had been allowed to succeed with the rest of the southern states, the capital of Washington would be located behind enemy lines.To secure the state, Lincoln sent General Benjamin Butler to occupy important positions throughout the state. On May 5 th, 1861 General Butler sent the 8 th New York & 6 th Massachusetts Regiments and Cook's Battery to Relay to protect the Railroad property from attack or sabotage by the South.

Fort Dix