To calculate the population density, you can use the formula:
\[ \text{Population Density} = \frac{\text{Population}}{\text{Area}} \]
Given that the population of Phoenix is 1,445,632 and the area is 450 square miles, the calculation would be:
\[ \text{Population Density} = \frac{1,445,632}{450} \approx 3,211.4 , \text{people per square mile} \]
So, the population density of Phoenix is approximately 3,211.4 people per square mile.