How is density determined?

Divide the number of people(or units) by the number of square miles(or area) they inhabit. (example: 8,000,000 new yorkers/322 square miles = population density of 24,845/sq.mi.) People divided by square miles Example: There are about 13000 people in New Ulm, MN. A town covering approximately 10 mi2. 13000/10=1300 people/sq mi