Few developments had the same impact on the United States as the expansion of railroads. By 1860, the United States had more railroad track than any other country in the world. At the same time, currency was evolving. Between 1861 and 1865, Confederate Currency was issued and backed by cotton, but it was worthless by the end of the Civil War. Coins were hoarded, leading Congress to authorize the use of postage stamps and the issuance of "Fractional Currency" as substitutes for coins.