What is a 1999 US penny worth?

A 1999 US penny is generally worth its face value of one cent if it's in circulation. However, if it's in uncirculated condition or has particular varieties, such as the "wide AM" or "close AM" types, it could be worth more to collectors, ranging from a few cents to several dollars. For accurate valuation, it's best to consult a coin dealer or a price guide.