Despite the fire’s devastation, much of Chicago’s physical infrastructure, including its water, sewage and transportation systems, remained intact. Reconstruction efforts began quickly and spurred great economic development and population growth, as architects laid the foundation for a modern city featuring the world’s first skyscrapers. At the time of the fire, Chicago’s population was approximately 324,000; within nine years, there were 500,000 Chicagoans. By 1893, the city was a major economic and transportation hub with an estimated population of 1.5 million. That same year, Chicago was chosen to host the World’s Columbian Exposition, a major tourist attraction visited by 27.5 million people, or approximately half the U.S. population at the time.