# The population density index
- **The population density index (population per square kilometer of land area)** measures the number of people divided by the land area in square kilometers.
- The graph shows the **population density rates** for **Monaco** and **Bahrain**, which are considered to have **high population densities**, over a decade from **2012 to 2021**.
- **Monaco** has the **highest population density in the world** due to its **small land area and large population**.