Dams in the United States

Caitlin Dempsey

Updated:

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.

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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.

A map of the United States with the location of dams shown as small orange circles.  The surrounding ocean is light blue.
A map of the distribution of dams in the United States. Map: Caitlin Dempsey, Data: National Inventory of Dams, U.S. Army Corps of Engineers.

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

StateTotal Number of Dams
Alabama2,266 
Alaska110 
Arizona375 
Arkansas1,266 
California1,526 
Colorado1,974 
Connecticut844 
Delaware83 
Florida993 
Georgia5,455 
Guam
Hawaii129 
Idaho409 
Illinois1,639 
Indiana1,092 
Iowa4,054 
Kansas6,456 
Kentucky1,089 
Louisiana685 
Maine584 
Maryland425 
Massachusetts1,327 
Michigan1,047 
Minnesota1,205 
Mississippi6,114 
Missouri5,366 
Montana3,005 
Nebraska2,938 
Nevada508 
New Hampshire653 
New Jersey828 
New Mexico401 
New York1,915 
North Carolina3,513 
North Dakota959 
Ohio1,391 
Oklahoma5,021 
Oregon887 
Pennsylvania1,493 
Puerto Rico36 
Rhode Island235 
South Carolina2,410 
South Dakota2,572 
Tennessee1,238 
Texas7,352 
Utah852 
Vermont371 
Virginia2,758 
Washington823 
West Virginia561 
Wisconsin1,000 
Wyoming1,523 
Total91,757 
Source: National Inventory of Dams, U.S. Army Corps of Engineers, November 3, 2022

Tile grid map of the number of dams by state

This tile grid map visualizes the number of dams for each U.S. state.

A map with each of the states as a square showing the number of dams per state. Texas, which has the most is shaded dark blue and states with the least are light green.
A tile grid map visualizing the number of dams per state. States with the highest number of dams are dark blue and states with the light number of dams are light green. Map: Caitlin Dempsey.

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

Side by side satellite images showing the water level in Lake Oroville between June 2019 (left) and June 2021 (right).
Side by side satellite images showing the water level in Lake Oroville between June 2019 (left) and June 2021 (right). Images: NASA, Landsat.

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About the author
Caitlin Dempsey
Caitlin Dempsey is the editor of Geography Realm and holds a master's degree in Geography from UCLA as well as a Master of Library and Information Science (MLIS) from SJSU.

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