As of the census of 2000, there were 3,705 people, 1,659 households, and 1,088 families residing in the CDP. The population density was 132.0 people per square mile (51.0/km). There were 2,485 housing units at an average density of 88.5 per square mile (34.2/km). The racial makeup of the CDP was 78.70% White, 0.24% Black or African American, 6.88% Native American, 0.30% Asian, 0.08% Pacific Islander, 9.15% from other races, and 4.64% from two or more races. 37.57% of the population were Hispanic or Latino of any race.
There were 1,659 households out of which 19.7% had children under the age of 18 living with them, 51.4% were married couples living together, 10.6% had a female householder with no husband present, and 34.4% were non-families. 30.1% of all households were made up of individuals and 17.1% had someone living alone who was 65 years of age or older. The average household size was 2.23 and the average family size was 2.74.
In the CDP the population was spread out with 20.6% under the age of 18, 4.9% from 18 to 24, 17.2% from 25 to 44, 25.3% from 45 to 64, and 32.1% who were 65 years of age or older. The median age was 52 years. For every 100 females there were 90.3 males. For every 100 females age 18 and over, there were 88.3 males.
The median income for a household in the CDP was $25,618, and the median income for a family was $29,310. Males had a median income of $28,000 versus $18,571 for females. The per capita income for the CDP was $14,548. About 16.5% of families and 22.3% of the population were below the poverty line, including 36.5% of those under age 18 and 9.0% of those age 65 or over.
Though Casas Adobes is an unincorporated community, it is older than both the towns of Oro Valley and Marana. Casas Adobes is notable for having the upscale shopping center, Casas Adobes Plaza, its only shopping mall, Foothills Mall, a major hospital, Northwest Medical Center, and the only botanical park, Tohono Chul Park. Casas Adobes primarily consists of homes situated on large lots (often in excess of 1 acre (4,000 m2)), and is suburban in character.
Established in the 1940s, the Casas Adobes community has grown to encompass a 23-square-mile (60 km2) area inhabited by nearly 60,000 residents. Casas Adobes takes its name from a large residential subdivision of the same name developed by Silvio "Sam" Nanini and his family. Most of the homes in the subdivision are large ranch-style homes built with adobe bricks.
However, the history of the Casas Adobes area predates the arrival of Sam Nanini. The area bordering the Caada del Oro in the north, and the Rillito River in the south was primarily inhabited and utilized by cattle ranchers. Cattle ranches dominated the Casas Adobes area until the 1920s, when Tucson had grown far enough north and the advent of the automobile made the area more easily accessible.
One of the first individuals to build a home in the area was Maurice L. Reid, who came to Tucson in 1923 seeking a "walking cure" for tuberculosis. In the late 1920s Reid bought a 1,500 acres (6.1 km2) former ranch, bounded by North Oracle Road to the east, Orange Grove Road to the south, Ina Road to the north, and North La Cholla Boulevard to the west. Reid planted more than 200 acres (0.81 km2) of citrus trees and date palms, that would become the heart of Tucson's citrus industry. Over the years, Reid sold parcels of land for home sites, and in 1950 he sold the last of his land. Some larger residential estates continue to maintain the remaining citrus groves and orchards nearly a century later.
Leonie Boutall, who relocated to Arizona from Tennessee, decided to build a guest ranch in the early 1930s. The dry climate, her doctor told her, would relieve her bronchial troubles. Boutall bought 100 acres (0.40 km2) of former ranch land just west of North Oracle Road, and south of a narrow dirt track now called Orange Grove Road. She built Rancho Nezhone, a luxury guest ranch that drew the rich and famous to the sparsely settled area far north of Tucson. Kate Smith, Liberace, Gen. John Pershing and William "Hopalong Cassidy" Boyd were guests of the desert retreat. Boutall sold out of the property in 1948.
In the late 1940s, further north along Oracle Road, Sam Nanini would ultimately make his mark in the area. Nanini and his wife, Giaconda, moved to Tucson in 1948 seeking to cure Giaconda Nanini's bronchial asthma. Beginning in the mid-1950s, the Italian born, transplanted Chicagoan developed three residential subdivisions on about 300 acres (1.2 km2) that became the heart of the Casas Adobes community, giving the community its name. The subdivisions, along with Sam Naninis landmark Casas Adobes Plaza, were considered by many to be Tucson's first suburb. Sam Nanini and his son William also later built the world-class Tucson National Resort, and the million-dollar residential subdivision, the Tucson National Estates.
While Casas Adobes' neighboring municipalities of Oro Valley, Marana and Tucson continue to build new homes and shopping centers, Casas Adobes is mostly built out. An attempt to incorporate the community failed in 2001, and it is likely that one or all three of the neighboring entities will annex portions of Casas Adobes in the future.