Monrovia, capital, largest city, and chief Atlantic port of Liberia, located on Bushrod Island and Cape Mesurado. It was founded during the administration of U.S. Pres. James Monroe (for whom it was named) by the American Colonization Society as a settlement for freed American slaves. The first town (1822) was on Providence Island at the mouth of the Mesurado River. The population is composed of descendants of settlers from North America, most of whom arrived between 1830 and 1871, and of substantial numbers of immigrants from the interior.