All 50 states in the United States have rivers with dams on them. A dam is a barrier built across a river or a stream that restricts the flow of water.
Dams are constructed for a variety of reasons varying from hydropower to creating reservoirs for the storage of water for agricultural, residential, and industrial purposes.
How many dams are there in the United States?
The U.S. Army Corps of Engineers (USACE) maintains an inventory of the location and state of dams in the United States. Known as the National Inventory of Dams (NID), this database contains information about each dam including its geographic location, who owns the dam, the type of dam, and its age.
There are, at last count, 91,757 dams in the United States (including Guam and Puerto Rico). Of those dams, almost 65% are private (a total of 59,600). 18,442 are owned by local governments, 6,690 are owned by state governments, and 3,432 are federally owned.
70% of the country’s dams are regulated by state governments and another 6% are regulated at the federal level. The average age of dams in the United States is 60 years.
Only three percent of dams in the United States have hydropower. Most of the largest hydropower dams are located in the western United States.
Which states have the most dams?
According to the National Inventory of Dams (as of November 3, 2022), there are currently 91,720 total in the 50 states (there is also one dam listed for Guam and 36 dams for Puerto Rico).
Texas is the state with the most dams with 7,352 dams. That means 8% of all the dams in the United States are located in Texas.
Kansas has the second largest amount of dams with 6,456 followed by Mississippi with 6,114 dams.
Georgia (5,455) and Missouri round out the top five states with the most dams.
Which states have the least dams?
The state of Delaware has the least dams with 83, followed by Alaska with 110 dams.
Table: number of dams per state
|State||Total Number of Dams|
Tile grid map of the number of dams by state
This tile grid map visualizes the number of dams for each U.S. state.
Tallest dam in the United States
With a height of 770 feet (235 meters) the Oroville Dam located in the Sierra Nevada foothills in the Sacramento Valley is the tallest dam in the United States.
An embankment dam, Oroville Dam was completed in 1968 by the California Department of Water Resources. The dam is used for hydroelectric power, flood control, and impounds Lake Oroville which is California’s second largest water reservoir.
Related: California’s Drought is Driving Reservoirs to Near Historic Lows in 2021