1. Cities cover about 3% of the Earth's land, and about 56–57% of people worldwide currently live in cities.
    This figure is expected to rise to 68% by 2050.

2. Rome was the first city to have over a million people. But in 2024 it is estimated that there are approximately
    570 to 600 cities worldwide with populations exceeding 1 million people.

3. We usually think that cities are really just very large towns. But world-wide, population size is not the sole
    criterion for being a city. In the U.S. what is and what is not a city varies state by state. Some cities have
    populations under 10,000, while some towns may be larger but not legally designated as cities. The
    designation often depends on local laws rather than just size. Sometimes population centers must meet
    certain governance or infrastructural criteria to be called a city. Some places, especially in Europe, retain the
    designation "city" based on historical charters regardless of current size.

4. Currently the five largest cities in the United States are 1. New York City, N.Y. Population: Approximately
    8.5 million, 2. Los Angeles, California Population: Approximately 3.9 million. 3. Chicago, Illinois Population
    : Approximately 2.7 million, 4. Houston, Texas Population: Approximately 2.4 million, 5. Phoenix, Arizona
    Population: Approximately 1.7 million.

5. The five smallest U.S. cities with populations between 10,000 and 50,000 are 1. Bridgeton, New Jersey
    Population: About 27,000, 2. Oak Park, Illinois Population: About 54,000  3. Glendale, California Population
    : About 50,000 - 59,000 4. New Rochelle, New York Population: About 30,000  5. Santa Fe, New
    Mexico (the state capitol) Population: Around 40,000 - 45,000.

6. The United States has 4 state capitols with less than 25,000 population. They are 1. Montpelier, Vermont
    Population: About 7,500  2. Pierre, South Dakota Population: About 14,000  3. Augusta, Maine Population:
    About 18,600.

7. According to a 2024 estimate,no U.S. city appears in a list of the largest cities of the world. With the
    exception of Mexico City, no city in North America makes the list of the ten largest cities of the world. The
    ten largest cities in the world are, in order, Tokyo, Japan, Delhi, India, Shanghai, China, São Paulo, Brazil,
    Mexico City, Mexico, Cairo, Egypt, Mumbai, India, Beijing, China, Dhaka, Bangladesh, and Osaka, Japan.

8. The first recognized country not limited to a city-state was likely unified ancient Egypt around 3100 BCE.
    Before then most people lived in city states like those found in ancient Mesopotamia such as Uruk, Eridu
    and Ur.

9. Four city states still exist in modern times. They are Singapore, Monaco, Vatican City, and San Marino.