Tacna is a census-designated place in Yuma County, Arizona, United States. The population was 555 at the 2000 census, and 602 at the 555 at the 2010 census. It is part of the Yuma Metropolitan Statistical Area.Tacna is located at 32°41′45″N 113°57′47″W / 32.69583°N 113.96306°W / 32.69583; -113.96306.According to the United States Census Bureau, the CDP has a total area of 1.9 square miles, all of it land.As of the census of 2000, there were 555 people, 194 households, and 149 families residing in the CDP. The population density was 294.3 people per square mile. There were 281 housing units at an average density of 149.0/sq mi. The racial makeup of the CDP was 66.67% White, 1.08% Black or African American, 0.72% Native American, 0.54% Asian, 25.41% from other races, and 5.59% from two or more races. 50.81% of the population were Hispanic or Latino of any race.There were 194 households out of which 37.1% had children under the age of 18 living with them, 66.