| Official Name: | Río Abajo |
| Settlement Type: | Barrio |
| Pushpin Map: | Caribbean |
| Pushpin Map Caption: | Location of Puerto Rico |
| Coordinates: | 18.4297°N -66.3821°W |
| Coordinates Footnotes: | [1] |
| Subdivision Type: | Commonwealth |
| Subdivision Name: |  Puerto Rico |
| Subdivision Type1: | Municipality |
| Subdivision Name1: | Vega Baja |
| Unit Pref: | Imperial |
| Area Total Sq Mi: | 2.40 |
| Area Land Sq Mi: | 2.36 |
| Area Water Sq Mi: | 0.04 |
| Population As Of: | 2010 |
| Population Note: | Source: 2010 Census |
| Population Total: | 4795 |
| Population Density Sq Mi: | 2031.80 |
| Timezone: | AST |
| Utc Offset: | -4 |
| Elevation Ft: | 39 |
| Postal Code Type: | ZIP Code |
Río Abajo is a barrio in the municipality of Vega Baja, Puerto Rico. Its population in 2010 was 4,795.[2] [3] [4]
Río Abajo was in Spain's gazetteers[5] until Puerto Rico was ceded by Spain in the aftermath of the Spanish–American War under the terms of the Treaty of Paris of 1898 and became an unincorporated territory of the United States. In 1899, the United States Department of War conducted a census of Puerto Rico finding that the combined population of Río Abajo and Río Arriba barrios was 1,092.[6]