Located in south-central Cameron County, the city was named for the fresnos (Fraxinus berlandieriana)[5] scattered in the woods and along streams.

In 1912, Lon Hill, an early landowner, formed a company to develop a canal system that would use the Rio Grande to irrigate land for farming.

Railroad construction in the early 1900s began to bring settlers to the area, and by 1915, a post office was established.

Los Fresnos is located slightly south of the geographic center of Cameron County at 26°4′24″N 97°28′41″W / 26.07333°N 97.47806°W / 26.07333; -97.47806 (26.073216, –97.478164).

Thunderstorm activity occurs usually during the spring and fall when cold fronts cause instability with the region's warm climate.

The United States Postal Service operates the Los Fresnos Post Office.

The Los Fresnos Rodeo and the Cameron County Livestock Show is held annually on the third weekend in February.

[26] Los Fresnos Motocross Park has campsites available at the track to accommodate recreational vehicles and tents.

Little Graceland was located on West Highway 100 and contains a small collection of Elvis Presley memorabilia, including photos, posters, watches, and playing cards.