US Coastline: 95,471 Miles of Shoreline & Beaches

The United States holds 95,471 miles of shoreline when measuring the general coastline, and 88,633 miles when measuring only the tidal shoreline, according to measurements by the National Oceanic and Atmospheric Administration. The Atlantic coast runs 2,069 miles from the Canadian border in Maine to the southern tip of Florida, while the Pacific coast extends 7,623 miles from the Mexican border through California, Oregon, and Washington. The Gulf of Mexico coastline adds 1,631 miles across five states. Alaska contributes 6,640 miles of general coastline, and Hawaii adds 750 miles across its eight main islands.

The Mississippi River drains 1,245,000 square miles, approximately 40 percent of the contiguous United States. The river flows 2,340 miles from Lake Itasca in Minnesota to the Gulf of Mexico below New Orleans. At its mouth, the Mississippi discharges an average of 600,000 cubic feet per second, carrying sediment that has built the river's delta approximately 50 miles into the Gulf over the past 7,000 years. The Missouri River, the Mississippi's longest tributary, measures 2,341 miles from its headwaters in Montana, making the combined Missouri-Mississippi system 3,710 miles in length.

The Great Lakes contain 21 percent of the world's surface freshwater by volume. Lake Superior holds 2,900 cubic miles of water, Lake Michigan 1,180 cubic miles, Lake Huron 850 cubic miles, Lake Erie 116 cubic miles, and Lake Ontario 393 cubic miles. The lakes' combined surface area covers 94,250 square miles. Water flows from Superior through the St. Marys River, then through the Straits of Mackinac connecting Huron and Michigan, continuing through the St. Clair River and Detroit River into Erie, and finally through the Niagara River into Ontario before draining to the Atlantic via the St. Lawrence River. The lakes' shorelines total 10,210 miles.

Chesapeake Bay measures 200 miles from the Susquehanna River's mouth to the Atlantic Ocean, with a surface area of 4,479 square miles at high tide. The bay receives freshwater from 150 rivers and streams draining a watershed of 64,000 square miles across six states. The Susquehanna River contributes 50 percent of the bay's freshwater inflow. The bay's average depth is 21 feet, with the deepest channel reaching 174 feet off Bloody Point on the eastern shore. The estuary supports more than 3,600 species of plants, fish, and animals, including the blue crab harvest that averaged 57 million pounds annually between 2010 and 2020.

San Francisco Bay covers 1,600 square miles at high tide, making it the largest Pacific estuary in the Americas. The Sacramento and San Joaquin rivers drain 40 percent of California's land area into the bay through the Sacramento-San Joaquin Delta. The bay's depth averages 12 to 15 feet, with shipping channels dredged to 50 feet. The Golden Gate strait connects the bay to the Pacific Ocean through a gap one mile wide and 372 feet deep. Tidal currents through the Golden Gate move up to 6 knots during maximum flow.

The Colorado River carved the Grand Canyon over an estimated 5 to 6 million years, creating a gorge 277 miles long, up to 18 miles wide, and one mile deep at its deepest point. The river drops 2,200 feet in elevation through the canyon. Before construction of Glen Canyon Dam in 1963, the Colorado carried an average of 380,000 acre-feet of sediment annually through the Grand Canyon. The river now flows through 11 major dams between its headwaters in the Rocky Mountains and its historic mouth in the Gulf of California, though today most years the river runs dry before reaching the sea.

Niagara Falls straddles the border between New York and Ontario, with the American Falls measuring 1,060 feet wide and the Horseshoe Falls measuring 2,600 feet wide. The American Falls drops 70 to 110 feet depending on the rock accumulation at its base, while Horseshoe Falls drops 188 feet. An average of 750,000 gallons of water flows over the falls every second during daytime hours in the tourist season. Hydroelectric diversions reduce nighttime flow to 50,000 gallons per second. The falls have retreated approximately seven miles upstream from their original position at the Niagara Escarpment over the past 12,500 years.

The Everglades covers approximately 1.5 million acres in southern Florida, forming a slow-moving river 60 miles wide and 100 miles long flowing from Lake Okeechobee to Florida Bay. Water moves through the sawgrass marsh at a rate of approximately 100 feet per day. The ecosystem supports 68 threatened or endangered species, including the American crocodile, West Indian manatee, and Florida panther. Everglades National Park protects 1,508,976 acres, or approximately 20 percent of the original Everglades. The park receives an average of 60 inches of rainfall annually, with 70 percent falling between May and October.

The Pacific coast experiences a tidal range averaging 4 to 7 feet along California, increasing to 8 to 12 feet in the Pacific Northwest, and reaching 20 to 30 feet in parts of Alaska. The Atlantic coast sees tidal ranges of 3 to 6 feet along most of the eastern seaboard, increasing to 8 to 12 feet in Maine. The Bay of Fundy, which borders Maine, experiences the world's highest tides at up to 53 feet. The Gulf of Mexico has the smallest tidal ranges, averaging 1 to 2 feet along most of the coast.

Coastal water temperatures range from 40 to 50 degrees Fahrenheit off Maine in summer, 65 to 75 degrees Fahrenheit off the mid-Atlantic coast, and 80 to 85 degrees Fahrenheit in the Florida Keys. Pacific coastal waters measure 55 to 60 degrees Fahrenheit off northern California, 60 to 65 degrees Fahrenheit off southern California, and 50 to 55 degrees Fahrenheit off Washington and Oregon. The Gulf Stream current moves warm water northward along the Atlantic coast at speeds up to 5.6 miles per hour, moderating coastal temperatures from Florida to Cape Hatteras.

The Atlantic Intracoastal Waterway extends 1,200 miles from Norfolk, Virginia, to Key West, Florida, providing a protected passage for commercial and recreational vessels. The Gulf Intracoastal Waterway runs 1,050 miles from Carrabelle, Florida, to Brownsville, Texas. These channels maintain a minimum depth of 12 feet and a minimum width of 125 feet. The waterways connect natural rivers, bays, and sounds with man-made canals, requiring 15 locks to manage elevation changes along the Atlantic route.

Death Valley contains Badwater Basin, which sits 282 feet below sea level, the lowest point in North America. The basin receives an average of 2.36 inches of rain annually. Summer air temperatures in Death Valley have reached 134 degrees Fahrenheit, recorded at Furnace Creek on July 10, 1913. The valley formed through tectonic extension and faulting beginning approximately 30 million years ago. Lake Manly filled much of Death Valley to a depth of 600 feet during the Pleistocene ice ages, the last occurrence ending approximately 10,000 years ago.