The Harlem River is a navigable tidal strait

Strait

A strait or straits is a narrow, typically navigable channel of water that connects two larger, navigable bodies of water. It most commonly refers to a channel of water that lies between two land masses, but it may also refer to a navigable channel through a body of water that is otherwise not...

 in New York City

New York City

New York is the most populous city in the United States and the center of the New York Metropolitan Area, one of the most populous metropolitan areas in the world. New York exerts a significant impact upon global commerce, finance, media, art, fashion, research, technology, education, and...

, USA

United States

The United States of America is a federal constitutional republic comprising fifty states and a federal district...

 that flows 8 miles (13 km) between the Hudson River

Hudson River

The Hudson is a river that flows from north to south through eastern New York. The highest official source is at Lake Tear of the Clouds, on the slopes of Mount Marcy in the Adirondack Mountains. The river itself officially begins in Henderson Lake in Newcomb, New York...

 and the East River

East River

The East River is a tidal strait in New York City. It connects Upper New York Bay on its south end to Long Island Sound on its north end. It separates Long Island from the island of Manhattan and the Bronx on the North American mainland...

, separating the boroughs

Borough (New York City)

New York City, one of the largest cities in the world, is composed of five boroughs. Each borough now has the same boundaries as the county it is in. County governments were dissolved when the city consolidated in 1898, along with all city, town, and village governments within each county...

 of Manhattan

Manhattan

Manhattan is the oldest and the most densely populated of the five boroughs of New York City. Located primarily on the island of Manhattan at the mouth of the Hudson River, the boundaries of the borough are identical to those of New York County, an original county of the state of New York...

 and the Bronx

The Bronx

The Bronx is the northernmost of the five boroughs of New York City. It is also known as Bronx County, the last of the 62 counties of New York State to be incorporated...

. Part of the current course of the Harlem River is the Harlem River Ship Canal

Spuyten Duyvil Creek

Spuyten Duyvil Creek is a channel connecting the Hudson River to the Harlem River Ship Canal, and on to the Harlem River in New York City, separating the island of Manhattan from the Bronx and the rest of the mainland. The neighborhood named Spuyten Duyvil lies to the north of the creek.Spuyten...

, which runs somewhat south of the former course of the river, isolating a small portion of Manhattan (Marble Hill

Marble Hill, Manhattan

Marble Hill is the neighborhood which makes up the northernmost part of the Borough of Manhattan in New York City, United States. Although it is politically part of Manhattan and New York County, because of the re-routing of the Harlem River, it is located on the North American mainland contiguous...

) on the Bronx side of the river.
The Harlem River is spanned by seven swing bridges, three lift bridges, and four arch bridges, and is navigable to any boat with less than 55 feet (16.8 m) of air draft

Air draft

Air draft is the distance from the surface of the water to the highest point on a vessel, similar to the "deep draft" of a vessel which is measured from the surface of the water to the deepest part of the hull below the surface, but "air draft" is expressed as a height, not a depth.The vessel's...

.