The highest undulations are found along the coastal Miami Rock Ridge, whose substrate underlies most of the eastern Miami metropolitan region.
Miami and its metropolitan area grew from just over 1,000 residents to nearly 5.5 million residents in just 110 years (1896–2006).
The highest natural point in the city of Miami is in Coconut Grove, near the bay, along the Miami Rock Ridge at 24 feet (7.3 m) above sea level.
The surface bedrock under the Miami area is called Miami oolite or Miami limestone.
Julia Tuttle subsequently convinced Henry Flagler, a railroad tycoon, to expand his Florida East Coast Railway to the region, for which she became known as "the mother of Miami." Black labor played a crucial role in Miami's early development.
During the beginning of the 20th century, migrants from the Bahamas and African-Americans constituted 40 percent of the city's population.