The name Hongkou originates from Hongkou Port. Historically, the waterway was called Shahong, a tributary of the Huangpu River Shanghai’s “mother river” constantly flowing into it. The place where Shahong met the Huangpu was called “Hongkou” (the flood mouth). Later, a curved bridge was built over the water, its arch resembling a rainbow. People gave it the poetic name “Hongqiao” (Rainbow Bridge).