Crystal Lake is a census-designated place (CDP) in Polk County, Florida, United States. The population was 5,341 at the 2000 census, an increase from 5,300 in 1990. The 2010 Census reported a population of 5,514. It is part of the Lakeland–Winter Haven Metropolitan Statistical Area. Using only the above description and what you know about the world, "The population in Crystal Lake was higher in 1990 than in 1980." is definitely correct, incorrect, or inconclusive? 