Luna Pier is a city in Monroe County in the U.S. state of Michigan. The population was 1,382 at the 2020 census. Previously known as Lake…Luna Pier is a city in Monroe County in the U.S. state of Michigan. The population was 1,382 at the 2020 census. Previously known as Lakewood, it was established in the early 1900s and incorporated as a city in 1963.