when was the song rudolph the red-nosed reindeer written

The music for "Rudolph the Red-Nosed Reindeer" was written by Johnny Marks in 1948. However, it's important to note the following:

• Original Story: The character of Rudolph originated from a story written by Robert L. May in 1939 as an assignment for Montgomery Ward, a department store chain. May's story was included in a coloring book given away to promote the store.
• Song Adaptation: Johnny Marks, who was May's brother-in-law, saw the potential in the story and decided to adapt it into a song in 1948.

So, while the song itself was written in 1948, the core concept of Rudolph the Red-Nosed Reindeer originated from a story written in 1939.