<Ul> <Li> Central Highlands </Li> <Li> Cities </Li> <Li> Geology </Li> <Li> Islands </Li> <Li> Mountains </Li> <Li> (Extreme summits </Li> <Li> Ultra-prominent summits) </Li> <Li> Rivers </Li> <Li> Volcanoes </Li> <Li> Middle America </Li> <Li> Middle America Trench </Li> </Ul> <Li> (Extreme summits </Li> <Li> Ultra-prominent summits) </Li> <Li> Middle America Trench </Li>

When did central america become part of north america