 The recession year of 1922 saw a lower @-@ than @-@ usual demand for coins in commerce , and few cents were coined . At the time , dies were only made at Philadelphia ; the Denver Mint had outstanding orders for cents that year . When Denver applied to the Philadelphia Mint for more dies ( cents were not struck at either Philadelphia or San Francisco that year ) , it was told that the Philadelphia Mint could supply no more cent dies , as it was fully engaged in preparing dies for the Peace dollar . Denver filled its orders by striking with a worn @-@ out obverse die , which impressed the design fainter than usual . On many strikes , the mintmark on the die filled with oil and dirt , producing coins on which the mintmark does not appear , or appears only faintly . The 1922 plain piece is another relatively rare one in the Lincoln cent series . 
