5. Sodium-potassium pump: Protein mechanism found along the neuron membrane which transports 3 Na+ ions outside of the cell while also drawing 2 K+ ions into the cell; this is an active transport mechanism (requires energy (ATP) to function). 6.
What Is the Population Density of the United States? The population density of the United States is approximately 87.4 people per square mile, according to the 2010 U.S. Census. What Is the Most Densely Populated Continent? Perhaps not surprisingly, the most densely populated continent is Asia. Here are the population densities of the continents: 1  North America - 32 people per square mile. 2  South America - 73 people per square mile. 3  Europe - 134 people per square mile. 4  Asia - 203 people per square mile. 5  Africa - 65 people per square mile. 6  Australia - 6.4 people per square mile.
New estimates indicate 80.7 percent of Americans now reside in urban areas, up from 79 percent in 2000. Population density for these areas varies greatly, ranging from about 400 residents per square mile to more than 5,000 in larger cities. California is home to a significant number of the nationâs most densely-populated urbanized areas. Of the top 50 areas with the highest population density, all but 15 are located in the Golden State.