Aliso Viejo (; Spanish for "old alder tree") is a city in the San Joaquin Hills of southern Orange County, California. It had a population of 52,176 as of the 2020 census, up from 47,823 as of the 2010 census. It became Orange County's 34th city on July 1, 2001, the only city in Orange County to be incorporated since 2000. It is bordered by the cities of Laguna Beach on the west and southwest, Laguna Hills on the east, Laguna Niguel on the southeast, and Laguna Woods on the north. It is similarly named to another nearby city, Mission Viejo.
History
The Acjachemen are the Indigenous people of Aliso Viejo, who lived in the area for thousands of years. The people established numerous villages along Aliso Creek as well dividing the Acjachemen and the Tongva. With the arrival of settlers, the Acjachemen village sites would later become the southern areas of the Moulton Ranch.
The planned community of Aliso Viejo's original were once part of the Moulton Ranch, owned by the Moulton family, who took title in the 1890s to Rancho Niguel, originally granted to Juan Avila by the Mexican government in 1842. Over the years, portions of the ranch were sold and became Leisure World, Laguna Hills and Laguna Niguel.
Incorporation
Aliso Viejo had been an unincorporated community since 1979, and incorporated as a city in 2001 due to the efforts of the Aliso Viejo Cityhood 2000 Committee, which was responsible for introducing an initiative on the ballot for the 2001 special election. Voters passed the initiative with 93.3% in favor of incorporation. Carmen Vali-Cave, the co-founder and president of the committee, became the new city's first mayor.
The seal of the city of Aliso Viejo was adopted in 2001 at incorporation. The seal features several mountains, a sunset, a tree, and several buildings. Also, the seal features the slogan "July 2001", in celebration of the city's incorporation date.
Aliso Viejo is a general law city with a council-manager system of government. Day-to-day operations are handled by a professional city manager overseen by a volunteer city council. The City Council of Aliso Viejo consists of five members serving staggered four-year terms. Each year, the Council votes for its next Mayor and Mayor pro tem. The current City Council consists of Mayor Mike Munzing, Mayor Pro-Tem Tiffany Ackley, and Council Members David C. Harrington, Ross Chun, and William Phillips .
thumb|200px|right|Clock tower of the Aliso Viejo Library
State, Federal, and County Representation
In the California State Legislature, Aliso Viejo is in , and in .
In the United States House of Representatives, Aliso Viejo is in .
Additionally, in the Orange County Board of Supervisors, Aliso Viejo is in the 5th County District, represented by Katrina Foley since 2025.
Politics
Aliso Viejo is a swing city at the presidential level. According to the Orange County Registrar of Voters, as of May 15, 2025, Aliso Viejo has 33,064 registered voters. Of those, 9,210 (33.25%) are registered Republicans, 8,800 (31.77%) are registered Democrats, and 8,388 (30.28%) have declined to state a political party/are independents.
Crime
The Uniform Crime Report (UCR), collected annually by the FBI, compiles police statistics from local and state law enforcement agencies across the nation. The UCR records Part I and Part II crimes. Part I crimes become known to law enforcement and are considered the most serious crimes including homicide, rape, robbery, aggravated assault, burglary, larceny, motor vehicle theft, and arson. Part II crimes only include arrest data. The 2023 UCR Data is listed below:
{| class="wikitable"
|+2023 UCR Data
!
!Aggravated
Assault
!Homicide
!Rape
!Robbery
!Burglary
!Larceny
Theft
!Motor
Vehicle Theft
!Arson
|-
|Aliso Viejo
|44
|0
|0
|13
|39
|267
|54
|4
|}
{| class="wikitable" style="float:right; margin:1em; font-size:95%;"
|+ Aliso Viejo city vote<br/> by party in presidential elections
|- style="background:lightgrey;"
! Year
! Democratic
!Republican
! Third Parties
|-
|align="center" |2024
|align="center" |52.57% 13,480
|align="center" |43.96% 11,273
|align="center" |3.46% 888
|-
|align="center" |2020
|align="center" |56.48% 15,754
|align="center" |41.30% 11,519
|align="center" |2.22% 619
|-
|align="center" |2016
|align="center" |51.63% 10,968
|align="center" |40.99% 8,708
|align="center" |7.37% 1,566
|-
|align="center" |2012
|align="center" |47.27% 9,430
|align="center" |50.09% 9,991
|align="center" |2.64% 527
|-
|align="center" |2008
|align="center" |52.65% 10,645
|align="center" |45.54% 9,207
|align="center" |1.81% 366
|-
|align="center" |2004
|align="center" |40.73% 7,648
|align="center" |58.39% 10,964
|align="center" |0.88% 166
|}
Geography
Aliso Viejo is located at (33.575096, -117.725431) in the San Joaquin Hills of Orange County. According to the Census Bureau, the city has a total area of , all of which is land. Aliso Viejo is one of several cities bordering Aliso and Wood Canyons Regional Park. Aliso Creek forms part of the city's boundary with Laguna Niguel to the south, and Wood Canyon Creek forms part of the city's western boundary. Much of the city rests on the east slope of the San Joaquin Hills, which are a coastal mountain range extending for about along the Pacific coast.
Biogeography
The most common native species: Red Sand Verbena, Pink Sand Verbena, and Big Leaf Maple