North America is the third-largest continent in the world (just beating out South America). It covers approximately 24.5 million square kilometers and is home to such countries as Canada, the United States, and Mexico. North America is home to a diverse range of climates and ecosystems, including arctic tundra, boreal forests, grasslands, deserts, and tropical rainforests. The continent is also rich in natural resources, including oil, natural gas, timber, and ketchup. The three largest countries in North America—the United States, Canada, and Mexico—together form an “America sandwich,” with Canada as the top bun, the US as its meat, and Mexico as the bottom bun.