Where was the penny maked with a d made?

The penny marked with a "D" was made at the Denver Mint, which is located in Denver, Colorado. The "D" mint mark indicates that the coin was produced there, distinguishing it from pennies made at other mints, such as those with "P" for Philadelphia or "S" for San Francisco. This mint mark is a common feature on U.S. coins to identify their place of manufacture.