| Official Name: | St. Just |
| Settlement Type: | Barrio |
| Pushpin Map: | Caribbean |
| Pushpin Map Caption: | Location of Puerto Rico |
| Coordinates: | 18.3704°N -66.0025°W |
| Coordinates Footnotes: | [1] |
| Subdivision Type: | Commonwealth |
| Subdivision Name: |  Puerto Rico |
| Subdivision Type1: | Municipality |
| Subdivision Name1: | Trujillo Alto |
| Unit Pref: | Imperial |
| Established Title: | Founded |
| Established Date: | 1990 |
| Area Total Sq Mi: | 2.26 |
| Area Land Sq Mi: | 2.23 |
| Area Water Sq Mi: | 0.03 |
| Population As Of: | 2010 |
| Population Note: | Source: 2010 Census |
| Population Total: | 14635 |
| Population Density Sq Mi: | 6592.3 |
| Timezone: | AST |
| Utc Offset: | -4 |
| Elevation Ft: | 125 |
| Postal Code Type: | ZIP Code |
St. Just is a barrio in the municipality of Trujillo Alto, Puerto Rico. A newer barrio, its population is counted starting with the 2000 Census, and in 2010 was 14,635.[2] [3] [4]
A newer barrio of Trujillo Alto, it was established in 1990. The barrio is named after an Infantry Captain of the Spanish army, Federico Saint Just, who in 1818 and by royal decree was granted a large swath of land belonging to barrio Cuevas in Trujillo Alto.[5]