The United States had no national paper money until 1862 (greenbacks used to fund the Civil War), but these notes were discounted to gold until 1877. There was also a shortage of U.S. minted coins. Foreign coins, such as Mexican silver, were commonly used. At times banknotes were as much as 80% of currency in circulation before the Civil War. In the financial crises of 1818–19 and 1837–41, many banks failed, leaving their money to be redeemed below par value from reserves. Sometimes the notes became worthless, and the notes of weak surviving banks were heavily discounted. The Jackson administration opened branch mints, which over time increased the supply of coins. Following the 1848 finding of gold in the Sierra Nevada, enough gold came to market to devalue gold relative to silver. To equalize the value of the two metals in coinage, the US mint slightly reduced the silver content of new coinage in 1853.