The original Lock & Dam #26 was located about two miles upstream from the current Melvin Price Lock & Dam project. Completed in the late 1930s the Lock & Dam experienced problems right from the start. The river quickly scoured the rock under the dam, creating large holes. The holes eventually became deeper than the depth of the wooden piles upon which the dam rested. This lead to the dam walls settling. The structure was also prone of large movements during high water.

The only real solution to the problem at Lock & Dam #26 was replacement. The new Melvin Price Lock & Dam was started in 1978 and completed in 1994. The first lock opened in late 1989. The old structure was removed in 1990.

The primary lock is 1,200 feet long by 110 feet wide. An auxiliary lock is 600 feet long by 110 feet wide. This is one of the few Mississippi River structures to have two locks. The long primary lock allows tows to lock through the structure without having to break up the tow and lock the tow in several sections. This greatly speeds the locking process.

Public access is available on both the Illinois and Missouri sides of the river. The Illinois side features the National Great Rivers Museum, which tells the story of the meeting of the three great rivers.