| Mercado | |
| Image Alt: | Colorful outdoor kiosk with items for sale |
| Image Map1: | San Juan Antiguo.jpg |
| Map Caption1: | San Juan Antiguo is in San Juan |
| Pushpin Map: | Caribbean |
| Pushpin Map Caption: | San Juan is in Puerto Rico |
| Settlement Type: | Subbarrio |
| Subdivision Type: | Commonwealth |
| Subdivision Name: |  Puerto Rico |
| Subdivision Type1: | Municipality |
| Subdivision Name1: | San Juan |
| Subdivision Type2: | Barrio |
| Subdivision Name2: | San Juan Antiguo |
| Population Density Km2: | auto |
Mercado, located within Old San Juan, is one of 7 subbarrios in San Juan Antiguo barrio in the municipality of San Juan in Puerto Rico.
The name of this subdistrict comes from the Spanish word for marketplace, as Old San Juan's main marketplace used to be located here.
The United States took control of Puerto Rico from Spain in the aftermath of the Spanish–American War under the terms of the Treaty of Paris of 1898. In 1899, the United States conducted its first census of Puerto Rico, finding that the population of Mercado was 2,038.[1]