According to the United States Census Bureau, the city has a total area of 105.6 km² (40.8 mi²). 97.0 km² (37.4 mi²) of it is land and 8.7 km² (3.4 mi²) of it is water. The total area is 8.24% water.
As of the census of 2000, there are 78,247 people, 31,521 households, and 20,898 families residing in the city. The population density is 806.9/km² (2,090.2/mi²). There are 33,798 housing units at an average density of 348.5/km² (902.8/mi²). The racial makeup of the city is 86.55% White, 0.96% African American, 0.42% Native American, 4.24% Asian, 0.20% Pacific Islander, 4.65% from other races, and 2.99% from two or more races. 11.72% of the population are Hispanic or Latino of any race.
There are 31,521 households out of which 30.7% have children under the age of 18 living with them, 54.3% are married couples living together, 8.6% have a female householder with no husband present, and 33.7% are non-families. 24.8% of all households are made up of individuals and 8.2% have someone living alone who is 65 years of age or older. The average household size is 2.46 and the average family size is 2.96.
In the city the population is spread out with 23.3% under the age of 18, 6.2% from 18 to 24, 31.9% from 25 to 44, 24.6% from 45 to 64, and 14.0% who are 65 years of age or older. The median age is 39 years. For every 100 females there are 95.8 males. For every 100 females age 18 and over, there are 92.8 males.
The median income for a household in the city is $65,145, and the median income for a family is $77,151. Males have a median income of $54,826 versus $39,415 for females. The per capita income for the city is $34,863. 5.9% of the population and 3.4% of families are below the poverty line. Out of the total people living in poverty, 7.3% are under the age of 18 and 3.6% are 65 or older.
Carlsbad's history begins with the Luiseņo people who located one of their villages, Palamai, near what is today downtown Carlsbad. Modern-day Carlsbad came about when in the 1880s a former sea captain named John Frazier dug a well for water. He began hawking his water at the Old Santa Fe Depot and the soon the whistlestop became known as Frazier's Station. A test done on a second fresh-water well found the water to be chemically similar to one of the most famous spas in Europe located in Carlsbad, Bohemia.
To take advantage of this find, a partnership named the Carlsbad Land and Mineral Water Company was founded. It was headed by a German-born merchant from the Midwest named Gerhard Schutte. The renaming of the town followed soon-after along with a major marketing campaign to attract visitors. The area experienced a period of rapid growth and within six months time could claim among other things a newspaper, an elaborate train depot, several churches, schools and a telegraph and post offices.
But by the end of 1887, the real estate bubble had burst and land prices slid all throughout San Diego County. The community survived though, due in part to its mild climate, beautiful beaches and wonderful setting. The site of John Frazier's original well can still be found at Alt Karlsbad, a replica of a German Hanseatic house, located on Carlsbad Boulevard.