By Chuck Coker
May 4, 2024
Latest Update: September 24, 2025

Question: In the railroad section of the museum, there is a display of nails with numbers on them. I have some of nails like those. What are the nails used for?

The nail you have is a railroad date nail. Date nails were a quality-control measure that allowed railroads and tie manufacturers to determine the lifespan of wooden cross tie. Railroad date nails were first introduced in 1897 by the Mississippi River & Bonne Terre Railroad, and were common in the US from 1900 to 1969. A two-digit number indicated the year the tie, timber, or pole was manufactured.

Date nails came in round, square, diamond, and pentagon shapes. The numbers were both raised and inset, depending on railroad and/or nail manufacturer. Neither one was better than the other. Raised numbers could deform while being hammered into the wood, but inset numbers could fill with dirt and soot making them hard to read.

Two-digit numbers indicated the year and make up the vast majority on date nails. Other nails were called code nails. Single-digit nails were often used for numbering switches or other structural elements. Letters often referred to the tie condition or treatment method.

Steel was, by far, the most common material date nails were made from. Copper, iron, aluminum, and brass were also used. The heads were typically 1/2 to 5/8 inches in diameter with a shank 2 to 3 inches in length.

For Santa Fe, a date nail with a round head shape was used in treated ties and timbers. A square or a diamond (considered a square) head shape was used in untreated ties and timbers. A pentagon head shape was used in second-hand ties and timbers. When a tie was reused, the pentagon-headed nail showed the year the tie or timber was reused.

For Santa Fe, code nails had “ST” for Special Treatment or possibly Steam Treatment. “OZ” indicated Oil-Zinc treated. “ZM” indicated Zinc and creosote-petroleum Mixture treated. “X” indicated a Substandard tie.

A 1943 date nail in a cut-down utility pole. Photo by Cr4410/Wikipedia. Used under CC BY-SA 4.0 license.
A 1943 date nail in a cut-down utility pole.
Photo by Cr4410/Wikipedia. Used under CC BY-SA 4.0 license.
A 1943 date nail in a cut-down utility pole. Photo by Cr4410/Wikipedia. Used under CC BY-SA 4.0 license.
A 1943 date nail in a cut-down utility pole.
Photo by Cr4410/Wikipedia. Used under CC BY-SA 4.0 license.

Sources

Meyers, Rolland. Date Nails. Railway Tie Association. Undated. E-pub. https://www.rta.org/assets/docs/Other/date%20nail%20history%20cohs.pdf.

Oaks, Jeff. Date Nails and Tie Preservation, Vol. 1. Archeology and Forensics Laboratory, University of Indianapolis, 1999. E-pub. https://nailhunter.com/Volume1.pdf.

Oaks, Jeff. Date Nails and Tie Preservation, Vol. 2. Archeology and Forensics Laboratory, University of Indianapolis, 1999. E-pub. https://nailhunter.com/Volume2.pdf.

Oaks, Jeff. Date Nails and Tie Preservation, Vol. 3. Archeology and Forensics Laboratory, University of Indianapolis, 1999. E-pub. https://nailhunter.com/Volume3.pdf.

“Railroad Date Nails.” RelicRecord. May 13, 2017. https://relicrecord.com/blog/railroad-date-nails/.