The city of Dayton, platted in 1855, is named for city founder, Lyman Dayton (1810-1865). Through his energy and finances, Lyman Dayton was instrumental in bringing the railroad into Minnesota and development of the Lake Superior and Mississippi Railroad, of which he was President until 1865.
As of the census of 2000, there were 4,699 people, 1,550 households, and 1,292 families residing in the city. The population density was 200.4 people per square mile (77.4/km²). There were 1,566 housing units at an average density of 66.8/sq mi (25.8/km²). The racial makeup of the city was 95.28% White, 0.64% African American, 0.64% Native American, 0.81% Asian, 1.87% from other races, and 0.77% from two or more races. Hispanic or Latino of any race were 2.75% of the population. 31.6% were of German, 13.5% Swedish, 11.0% Norwegian and 7.9% Irish ancestry according to Census 2000.
There were 1,550 households out of which 45.7% had children under the age of 18 living with them, 71.9% were married couples living together, 7.9% had a female householder with no husband present, and 16.6% were non-families. 11.7% of all households were made up of individuals and 2.1% had someone living alone who was 65 years of age or older. The average household size was 3.03 and the average family size was 3.29.
In the city the population was spread out with 30.5% under the age of 18, 7.8% from 18 to 24, 33.2% from 25 to 44, 23.7% from 45 to 64, and 4.7% who were 65 years of age or older. The median age was 35 years. For every 100 females there were 103.1 males. For every 100 females age 18 and over, there were 105.1 males.
The median income for a household in the city was $66,875, and the median income for a family was $71,356. Males had a median income of $41,476 versus $30,386 for females. The per capita income for the city was $27,756. About 1.0% of families and 2.7% of the population were below the poverty line, including 3.7% of those under age 18 and none of those age 65 or over.