Lock and Dam No. 1

 dam, lock (water navigation)

Lock and Dam No. 1 on the Mississippi River is located between Minneapolis and Saint Paul, Minnesota just north of the confluence of the Mississippi with the Minnesota River. The dam portion is owned by the Ford Motor Company, which operates a hydroelectric power station to feed electricity to its Twin Cities Assembly Plant on the east side of the river. The dual-lock facility is operated by the St. Paul district of the U.S. Army Corps of Engineers' Mississippi Valley Division.

The first facility at the site went into operation in 1917 and superseded the role of the earlier Lock and Dam No. 2 (today known as the Meeker Island Lock and Dam). The facility was rebuilt in 1929, and an expansion from one lock to two locks was completed in 1932. Each lock is 56 feet wide by 400 feet long (17 × 122 meters), half the width of the next lock downstream, though this is the only dual-lock facility in the district. Major rehabilitation efforts were carried out between 1978 and 1983, including the replacement of many manual and hydraulic components with computer controls.

The eastern portion of the site consists of an overflow Ambursen dam, which is a buttress dam where the upstream part is a relatively thin flat slab usually made of reinforced concrete. There is an inflatable section on top of the dam that can slightly increase its size when so desired. The lock side of the facility has a large observation area that is open from April to November each year. A bridge allows visitors to walk over the two locks and right up next to the dam.

When the facility opened, it assured a navigable channel up to the tail end of Saint Anthony Falls upriver in Minneapolis. Additional locks were added there in the 1960s, extending the head of navigation to the northern part of the city. A dam in Coon Rapids prevents travel any further to the north.