According to the United States Census Bureau, the city has a total area of 15.1 km² (5.8 mi²), all land.
Based on archaeological findings it seems proven Tongva Indians hunted and fished in the area of today's Gardena. The Tongva Indians — also known as Gabrielino Indians — are probably descendants of those who crossed from Asia to North America around 10,000 years ago.
In 1784, three years after the foundation of Los Angeles a Spanish soldier named Juan Jose Rodriguez received, in recognition of his military service, land from the King of Spain. Part of this land contained what became known as Gardena Valley. After the American Civil War veterans bought parts of the land, soon ranchers and farmers followed suit. Civil War veteran Spencer Roane Thorpe is credited with starting the first settlement in Gardena in 1887. Some believe the city was named for its reputation for being the only "green spot" in the dry season between Los Angeles and the sea.
Railroads put Gardena on the map following a real estate boom in the Los Angeles area in the 1880s. Because of its acres of berries, the city was dubbed "Berryland". The Strawberry Day Festival and Parade was held each May annually. The berry industry suffered at the time of WWI as other crops were supported by the war economy.
The Los Angeles Basin is well-known for its year-round pleasant weather:
Gardena has a Mediterranean climate or Dry-Summer Subtropical (Köppen climate classification Csb on the coast, Csa inland). Gardena enjoys plenty of sunshine throughout the year, with an average of 263 sunshine days and only 35 days with measurable precipitation annually.
The period of April through November is warm to hot and dry with average high temperatures of 71 - 79°F and lows of 50 - 62°F. Due to the moderating effect of the ocean, temperatures are cooler than more inland areas of Los Angeles, where temperatures frequently exceed 90°F (32°C) and occasionally reach 100°F (38°C).
The Los Angeles area is also subject to the phenomena typical of a microclimate. As such, the temperatures can vary as much as 18°F (10°C) between inland areas and the coast, with a temperature gradient of over one degree per mile (1.6 km) from the coast inland. California has also a weather phenomenon called "June Gloom or May Grey", which sometimes brings overcast or foggy skies in the morning at the coast, but usually gives way to sunny skies by noon, during late spring and early summer.
The Los Angeles region averages 15 inches (385 mm) of precipitation annually, which mainly occurs during the winter and spring (November through April) with generally light rain showers, but sometimes as heavy rainfall and thunderstorms. Coastal areas receive slightly less rainfall, while the mountains receive slightly more. Snowfall is extremely rare in the city basin, but the mountains within city limits typically receive snowfall every winter.
As of the census of 2000, there were 57,746 people, 20,324 households, and 14,023 families residing in the city. The population density was 3,830.9/km² (9,921.3/mi²). There were 21,041 housing units at an average density of 1,395.9/km² (3,615.0/mi²). The racial makeup of the city was 23.82% White, 25.99% Black or African American, 0.64% Native American, 26.82% Asian, 0.73% Pacific Islander, 16.94% from other races, and 5.05% from two or more races. 31.82% of the population were Hispanic or Latino of any race.
There were 20,324 households out of which 33.5% had children under the age of 18 living with them, 44.5% were married couples living together, 18.1% had a female householder with no husband present, and 31.0% were non-families. 25.5% of all households were made up of individuals and 8.2% had someone living alone who was 65 years of age or older. The average household size was 2.80 and the average family size was 3.38.
In the city the population was spread out with 25.8% under the age of 18, 8.7% from 18 to 24, 32.3% from 25 to 44, 20.9% from 45 to 64, and 12.4% who were 65 years of age or older. The median age was 34 years. For every 100 females there were 95.1 males. For every 100 females age 18 and over, there were 91.4 males.
The median income for a household in the city was $38,988, and the median income for a family was $44,906. Males had a median income of $32,951 versus $29,908 for females. The per capita income for the city was $17,263. About 12.3% of families and 15.7% of the population were below the poverty line, including 22.3% of those under age 18 and 10.1% of those age 65 or over.
The Gardena Police Department is the primary law enforcement agency in the City. The Police Department has 93 sworn police officers, 24 full-time support staff, and 33 part-time employees. There are reserve, volunteer, and explorer programs. The current Chief of Police is Edward Medrano, appointed in 2007. Radio communications and the 9-1-1 call center are handled by the South Bay Regional Public Communications Authority.
In the state legislature Gardena is located in the 25th Senate District, represented by Democrat Edward Vincent, and in the 51st Assembly District, represented by Democrat Curren D. Price Jr.. Federally, Gardena is located in California's 35th congressional district, which has a Cook PVI of D +33 and is represented by Democrat Maxine Waters.
The United States Postal Service operates the Gardena Post Office at 1455 West Redondo Beach Boulevard, the South Gardena Post Office at 1103 West Gardena Boulevard, and the Alondra Post Office at 14028 Van Ness Avenue.