Statista : https://www-statista-com.aamu.idm.oclc.org/ (login required)
USA Quickfacts: https://www.census.gov/quickfacts/fact/table/US/PST045219
CIA World Factbook: https://www.cia.gov/library/publications/the-world-factbook/index.html
US Census Bureau : https://www.census.gov/
