Phillips County is one of the 64 counties in the U.S. state of Colorado. As of the 2010 census, the population was 4,442. The county seat is Holyoke. The county was named in honor of R.O. Phillips, a secretary of the Lincoln Land Company, who organized several towns in Colorado.
According to the U.S. Census Bureau, the county has a total area of 688 square miles (1,780 km), of which 688 square miles (1,780 km) is land and 0.1 square miles (0.26 km) (0.02%) is water.
As of the census of 2000, there were 4,480 people, 1,781 households, and 1,239 families residing in the county. The population density was 6 people per square mile (3/km²). There were 2,014 housing units at an average density of 3 per square mile (1/km²). The racial makeup of the county was 93.04% White, 0.20% Black or African American, 0.29% Native American, 0.40% Asian, 0.02% Pacific Islander, 4.71% from other races, and 1.34% from two or more races. 11.76% of the population were Hispanic or Latino of any race.
There were 1,781 households out of which 32.90% had children under the age of 18 living with them, 61.20% were married couples living together, 5.60% had a female householder with no husband present, and 30.40% were non-families. 27.50% of all households were made up of individuals and 14.30% had someone living alone who was 65 years of age or older. The average household size was 2.47 and the average family size was 3.01.
In the county, the population was spread out with 26.90% under the age of 18, 6.30% from 18 to 24, 25.30% from 25 to 44, 22.20% from 45 to 64, and 19.40% who were 65 years of age or older. The median age was 40 years. For every 100 females there were 93.40 males. For every 100 females age 18 and over, there were 90.50 males.
The median income for a household in the county was $32,177, and the median income for a family was $38,144. Males had a median income of $30,095 versus $18,682 for females. The per capita income for the county was $16,394. About 8.80% of families and 11.60% of the population were below the poverty line, including 14.70% of those under
age 18 and 7.20% of those age 65 or over.