According to the United States Census Bureau, the CDP has a total area of 4.2 square miles (10.7 km²), of which, 3.9 square miles (10.2 km²) of it is land and 0.2 square miles (0.6 km²) of it (5.54%) is water.
San Ildefonso Pueblo is located at the foot of the Pajarito Plateau just 12.87 km (8 miles) east from Los Alamos, New Mexico, 38.6 km (24 miles) NW of Santa Fe, New Mexico. A large volcanic outcroping lies directly north of San Ildefonso Pueblo, it is called the "Black Mesa." The Rio Grande runs through San Ildefonso Pueblo and the lowest elevation is approximately 1676 meters (5500 feet).
There were 150 households out of which 38.7% had children under the age of 18 living with them, 48.0% were married couples living together, 24.0% had a female householder with no husband present, and 20.7% were non-families. 15.3% of all households were made up of individuals and 6.7% had someone living alone who was 65 years of age or older. The average household size was 3.05 and the average family size was 3.43.
In the CDP the population was spread out with 31.4% under the age of 18, 10.0% from 18 to 24, 26.4% from 25 to 44, 22.5% from 45 to 64, and 9.6% who were 65 years of age or older. The median age was 32 years. For every 100 females there were 90.8 males. For every 100 females age 18 and over, there were 98.7 males.
The median income for a household in the CDP was $30,000, and the median income for a family was $30,972. Males had a median income of $19,792 versus $19,250 for females. The per capita income for the CDP was $11,039. About 19.1% of families and 14.9% of the population were below the poverty line, including none of those under age 18 and 50.0% of those age 65 or over.
The Spanish conquistadors tried to subdue the native people and force their religion on the native people during the early 1600’s, which lead to the Pueblo Revolt of 1680. The people withstood the Spaniards by climbing to the top of the Black Mesa. The siege ended with the surrender of the native people, but the Spanish gave the native people some freedom of religion and other self-governing rights.
The pueblo natives continued to lead an agricultural based economy until the early 1900’s when Maria Martinez and her husband Julian Martinez rediscovered how to make the Black-on Black pottery for which San Ildefonso Pueblo would soon become famous. From that time the pueblo has become more tourist-oriented, with numerous tourist shops existing in the Pueblo. Because of close proximity to the state capital, Santa Fe, and the presence of the Los Alamos National Laboratory, many of those employed in the pueblo have government jobs.