| Missouri Key | |
| Nickname: | --> |
| Pushpin Map: | Florida#Caribbean |
| Pushpin Label Position: | left |
| Pushpin Relief: | 1 |
| Pushpin Map Caption: | Missouri Key |
| Location: | Gulf of Mexico |
| Archipelago: | Florida Keys |
| Waterbody: | Florida Straits |
| Country Admin Divisions Title: | State |
| Country Admin Divisions: | Florida |
| Country Admin Divisions Title 1: | County |
| Country Admin Divisions 1: | Monroe |
Missouri Key is a small island in the lower Florida Keys.[1]
U.S. 1 (or the Overseas Highway) crosses the key at approximately mile marker 39.5, between Ohio Key and Little Duck Key.
The island was named during Henry Flagler's Overseas Railroad construction years by workers from that state.
It is sometimes known locally as Little Grassy Key or Grassy Island.