Lock and Dam No. 3 is a lock and dam located near Red Wing, Minnesota on the Upper Mississippi River around river mile 796.9. It was constructed and placed in operation July 1938. The site underwent major rehabilitation from 1988 through 1991. The dam is 365 feet (111.3 m) long with 4 roller gates. More than 2,000 feet (609.6 m) of earth embankment with a series of upstream spot dikes completes the structure to create Pool 3. The lock chamber is 110 feet (33.5 m) wide by 600 feet (182.9 m) long. The lock and dam is owned and operated by the St. Paul District of the United States Army Corps of Engineers-Mississippi Valley Division.

Many types of vessels use the lock which annually passes more than 11 million tons of cargo, including farm products, chemicals and crude materials as the main items shipped. Each year more than 20,000 recreational craft use Lock 3, making it one of the most popular locks on the river. Also, a number of boats involved with fishing tournament utilize the lock.

• Public Works Administration dams list
• Prairie Island Indian Community

• U.S. Army Corps of Engineers, St. Paul District Lock and Dam 3
• U.S. Army Corps of Engineers, St. Paul District: Lock and Dam 3 brochure
• Historic American Engineering Record (HAER) No. MN-21, "Upper Mississippi River 9-Foot Channel Project, Lock & Dam No. 3, Red Wing, Goodhue County, MN", 98 photos, 11 data pages, 7 photo caption pages