As of the census of 2000, there were 3,065 people, 1,253 households, and 844 families residing in the city. The population density was 1,242.1 people per square mile (479.1Square kilometers). There were 1,458 housing units at an average density of 590.9 per square mile (227.9Square kilometers). Newcastle is a city in and the county seat of Weston County, Wyoming, United States. The population was 3,065 at the 2000 census. According to the United States Census Bureau, the city has a total area of 2.5square miles (6.4Square kilometers), all land.