Late in 1861, seeking to raise revenue for the American Civil War effort without exhausting its reserves of gold and silver, the United States federal government suspended specie payments, or the payments made in gold and silver in redemption of currency notes. Early in 1862, the United States issued legal-tender notes, called greenbacks. By war's end, a total of $431 million in greenbacks had been issued, and authorization had been given for another $50 million in small denominations, known as fractional currency or "shin plasters." The issuance of greenbacks caused inflation during the period.