*NEW: SLEUTH Online Data Repository*

Gigalopolis is the growing urban structure containing billions of people worldwide. Urban settlements and their connectivity will be the dominant driver of global change during the twenty-first century. Intensely impacting land, atmospheric, and hydrologic resources, urban dynamics has now surpassed the regional scale of megaloplolis and must now be considered as a continental and global scale phenomenon. Project Gigalopolis extends and refines the Clarke urban growth model enabling predictions at regional, continental and eventually global scales.