For much of its life, the penny was produced in three different mints. Most of the 1909 Lincoln pennies were produced in Philadelphia, where the presses stamped no identifying "mintmark" on the coins. A smaller number, produced in San Francisco, were marked by the single letter S. Coins minted in Denver — starting in 1911 — bore the stamp D. Production today is divided between two mints, Denver and Philadelphia, and has grown speedier: the U.S. Mint took more than two years to produce its first million coins, but today the Philadelphia Mint can make approximately that many in 45 minutes.