Peter:
I once purchased many of those among some trains I bought. I have since learned that those are the earliest of the early O Gauge tracks manufactured by Lionel. I don't know the exact date the ties started to be blackened, but the non-blackened ones likely range from 1915-1928.
The track I have happens to be in excellent shape. I try to keep them all together on a back straight way to see who notices them...
Enjoy,
Steven J. Serenska