Inwood is physically bounded by the Harlem River to the north and east, and the Hudson River to the west. It extends southward to Fort Tryon Park and alternatively Dyckman Street or Fairview Avenue farther south, depending on the source.
Notably, while Inwood is the northernmost neighborhood on the island of Manhattan, it is not the northernmost neighborhood of the entire borough of Manhattan. That distinction is held by Marble Hill, a Manhattan neighborhood situated just north of Inwood, on what is properly the North American mainland bordering the Bronx. (Marble Hill was isolated from Inwood and the rest of Manhattan in 1895 when the route of the Harlem River was altered by the construction of the Harlem River Ship Canal.)
Because of its water boundary on three sides, the hilly geography, and the limited local street connections (only Broadway and Fort George Hill connect to the rest of the Manhattan street grid), the neighborhood can feel somewhat physically detached from the rest of the borough. The W.P.A. Guide to New York City, published in the 1930s, described Inwood with "rivers and hills insulate a suburban community that is as separate an entity as any in Manhattan."
Inwood's main local thoroughfare is Broadway, which is also designated US 9 at this point. Highway access to the area is via the Henry Hudson Parkway to the west, the Harlem River Drive to the southeast (ending at Dyckman Street), the Alexander Hamilton Bridge over the Harlem River from the Trans-Manhattan Expressway to the Cross Bronx Expressway, the Washington Bridge at 181st Street crossing the Harlem River to the Bronx, the University Heights Bridge from 207th Street in Manhattan across the Harlem River to Fordham Road in the Bronx, and the Broadway Bridge across the Harlem River north to Marble Hill. Inwood's main commercial shopping streets are Broadway, Dyckman Street and West 207th St. The majority of neighborhood residents commute via the subway using either the A train at the 207th Street or Dyckman Street stations along Broadway or the 1 train at the Dyckman Street, 207th Street, or 215th Street stations along Tenth Avenue. The station at 207th Street and Broadway has been the northernmost terminus for the A train since it opened in 1932 and was renovated in 1999 to be ADA accessible. Inwood is also served by the M100, Bx7, Bx12+, and Bx20 bus routes. All routes except the Bx7 terminate in the neighborhood. The median commute time for all residents is approximately 45 minutes with 72.5% of residents working in New York County.
Inwood marble, a soft, white, metamorphic rock found in northern Manhattan, takes its name after the neighborhood. From the mid-17th to the late 18th century, commercial quarries dotted the area as the material was used for building construction. However, due to its susceptibility to erosion, builders eventually used alternate construction materials. Inwood marble was quarried for government buildings in lower Manhattan and Washington, D.C. Small pieces of marble can still be seen in the stone retaining walls around Isham Park.