The population density is given by the following quotient:
[tex]\text{ population density}=\frac{\text{ population}}{\text{ area}}_{}[/tex]Then the population density of the US is:
[tex]US=\frac{310000000}{3539225}=87.59\frac{\text{people}}{mile^2}[/tex]For Mexico this quantity is:
[tex]MX=\frac{122000000}{742485}=164.31\frac{\text{people}}{mile^2}[/tex]This means that according to this data Mexico has more population density than the US.