Watrous is an unincorporated community and census-designated place in Mora County, New Mexico, United States. Its population was 99 as of the 2020 census, down from 135 in 2010. Watrous has a post office with ZIP code 87753, which opened on April 14, 1868. The community is located along Interstate 25. It was named after merchant and landowner Sam…Watrous is an unincorporated community and census-designated place in Mora County, New Mexico, United States. Its population was 99 as of the 2020 census, down from 135 in 2010. Watrous has a post office with ZIP code 87753, which opened on April 14, 1868. The community is located along Interstate 25. It was named after merchant and landowner Samuel Watrous, who moved to New Mexico from Vermont in 1835.