When I visited Barstow CA in late July, I visited the Mojave River Valley Museum. Barstow is a historic railroad town, as well as a stop on historic Route 66. The Museum had date nails for sale.
Date nails were first used in Europe in the late 1800s to document different kinds of wood and treatment used for railroad ties. The Santa Fe Railroad was the first to use them in the United States, in 1901. I spent 30 minutes looking through the Museum’s nails to find either one from my birth year of 1955 or the oldest one available. The last date nails were used in 1969, and those dated 52, 55, 57, and 59 are the rarest and most expensive. I wound up with a 1923 nail.