Deciphering mile posts along the tracks

Guest post by Richard C. Carpenter.

When we drive along the interstate highway system, we measure our progress by mile markers, which are placed just off the right shoulder of the roadway. Interstate standards require that they be measured from zero at the state line and run to the next state line—west to east and south to north.

Railroads have long had their mile markers, too. They are called mile posts. These mile posts are the geographical measure of a railroad line. Their zero mile post locations and their end points often tell us something about the history of the line. Mile posts allow train crews to determine their exact location along otherwise nondescript stretches of geography.

They are also referenced when numbering bridges, and used to define the limits of speed restrictions.

Each railroad has its own style of mile post and its own way of numbering mile posts. Several railroads use their mile posts to measure every main and branch line from one zero location. For the Southern Pacific, mile post zero is San Francisco, 3rd and Townsend Streets. In the case of the Seaboard Air Line, zero is Richmond, Virginia. The Lehigh Valley (LV) mile posts start at the ferry slip on the New York side of the Hudson River, across from their Jersey City terminal station. On the LV posts, the mile number is cut in a metal diamond at the top of a thin pipe, then painted black.

Here are some specific examples, by railroad, of mile post styles and their start and end points.

The New York Central mile posts were stone or concrete, in the shape of a headstone. Some were unpainted, with a letter or letters for the origin point (ex.: “NY” for New York City) and the mileage cast in the concrete. Others were painted white with black letters and numbers. The original main line ran between New York City and Buffalo, New York, and were measured from zero at Grand Central Terminal in New York City to mile post 439 at Buffalo. The letters “NY” stood above the mileage numerals.

In 1914, the New York Central merged the Lake Shore and Michigan Southern into its system. The Lake Shore’s mile posts started at Buffalo and ended at mile post 540 at La Salle Street Station in Chicago. The letter “B” signified the zero point at the train’s Exchange Street Station in Buffalo. Originally, the mile post mileage west of Elyria, Ohio, was via the original LSMS line through Bellevue to Millbury, Ohio. West of Air Line Junction, in Toledo, the original milepost mileage ran through Sturgis, Michigan to Elkhart, Indiana.

This resulted in a total mile post mileage of 540 miles, as indicated above. These two segments were later referred to as the “Old Road,” to distinguish them from the Sandusky main line and the “Air Line” main line, both of which were built later. Sometime after 1946, the New York Central changed the mile post numbering west of Elyria Junction, Ohio via Sandusky and via the “Air Line” west of Toledo to be from Buffalo, so as to create a unified mile post series.

This resulted in a mile post mileage 18 miles shorter a than the original LSMS mile post mileage!

The Pennsylvania Railroad used a cast metal mile post, with a sloped top facing the track, and sides angled so the the cast number on each side would be visible from both directions. The bottom was slightly wider than the top. The mile post was painted white, with the mile numbers painted black. These mileposts were cast in the foundry of the PRR system shops in Altoona, PA

The original PRR main line started with the zero milepost at Broad Street Station, Philadelphia, and ran via Harrisburg and Altoona to mile post 353 at Pittsburgh. West of Pittsburgh, the mileposts ran from zero at Pittsburgh to mile post 467, south of Union Station, Chicago.

This latter line was originally the Pittsburgh, Fort Wayne and Chicago, which became part of the PRR in 1869.

Read part two of Richard Carpenter’s description of mile posts tomorrow.

Below are some maps from Richard C. Carpenter’s Railroad Atlas of the United States in 1946

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