| Official Name: | Río Abajo |
| Settlement Type: | Barrio |
| Pushpin Map: | Caribbean |
| Pushpin Map Caption: | Location of Puerto Rico |
| Coordinates: | 18.1412°N -65.7872°W |
| Coordinates Footnotes: | [1] |
| Subdivision Type: | Commonwealth |
| Subdivision Name: |  Puerto Rico |
| Subdivision Type1: | Municipality |
| Subdivision Name1: | Humacao |
| Unit Pref: | Imperial |
| Area Total Sq Mi: | 7.97 |
| Area Land Sq Mi: | 5.86 |
| Area Water Sq Mi: | 2.11 |
| Population As Of: | 2010 |
| Population Note: | Source: 2010 Census |
| Population Total: | 7495 |
| Population Density Sq Mi: | 1279 |
| Timezone: | AST |
| Utc Offset: | -4 |
| Elevation Ft: | 7 |
| Postal Code Type: | ZIP Code |
| Postal Code: | 00791 |
Río Abajo is a barrio in the municipality of Humacao, Puerto Rico. Its population in 2010 was 7,495.[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 population of Río Abajo and Mambiche barrios was 1,289.[6]
In 2019, updated flood zone maps show that because of its location- where many hurricanes enter the island, Humacao is one of the most vulnerable areas of Puerto Rico.[7] Humacao was working on flood mitigation plans and shared that its barrios located on the coast; Antón Ruíz, Punta Santiago, Río Abajo, Buena Vista and Candelero Abajo barrios, are prone to flooding and in danger of being completed destroyed by a hurricane.[8]