The Isthmus of Panama: Central America's Land Bridge

Defining Feature of Central America

The Isthmus of Panama is the narrow land bridge connecting North and South America. It is the only continental connection between the two landmasses.

Key Facts

• Width: ~50 km (31 mi) at narrowest (Culebra Cut area); ~100 km (62 mi) at widest
• Length: ~650 km (400 mi) from Costa Rica border to Colombia border
• Countries: Entirely within the Republic of Panama
• Elevation: Low saddle (max ~300 m) flanked by volcanic arcs (Central America Volcanic Arc)

Panama Canal: Global Chokepoint

• Completed 1914 (U.S.); expanded 2016 (New Panamax locks)
• Connects Atlantic (Caribbean) and Pacific Oceans
• ~14,000 transits/year; 6% of world maritime trade
• Major revenue for Panama; strategic military/commercial asset

Geological & Biogeographic Significance

• Great American Biotic Interchange (GABI): ~3 Ma closure allowed mammal migration (north: armadillos, opossums; south: cats, horses, llamas)
• Separated marine faunas → distinct Caribbean vs. Eastern Pacific ecosystems
• Ongoing tectonic activity: subduction of Cocos/Nazca plates under Caribbean Plate

Other Central American Isthmuses

Strictly, the entire Central American landmass is an isthmus. But "the Isthmus" = Isthmus of Panama. The Isthmus of Tehuantepec (Mexico) is the narrowest part of North America, not Central America.