Blue Rapids is a city in Marshall County, Kansas in the United States. The population was 1,088 at the 2000 census. Located on highway US-77/K-9, Blue Rapids is 5 miles (8.0 km) east of its sister town Waterville, 12 miles (19 km) south of the county seat Marysville, 13 miles (21 km) west of Frankfort, and 46 miles (74 km) north of the large university town of Manhattan.