The United States Customhouse is a historic and active custom house at 2nd and William Streets in New Bedford, Massachusetts.

By 1825, New Bedford had surpassed Nantucket as the world capital of the whaling industry, a distinction it would hold for much of the nineteenth century.

Custom House is attributed to Robert Mills (1781–1855), architect of the U.S. Treasury Building and the U.S. Patent Office in Washington, DC.

Custom Houses are similar in scale, plan, materials, and detailing, the New Bedford building is the largest and most architecturally elaborate.

Custom House in New Bedford, erected between 1834–1836, is an exceptional illustration of a modest public building designed in the Greek Revival style.

Seeking to end the onslaught of fires, the Treasury Department instituted new requirements for fireproofing federal buildings.

The structure has granite-faced, masonry-bearing walls with floors supported by brick groin-vaults and a hipped roof carried by zinc-coated wood trusses.

The high-style portico, which is characteristic of the Greek Revival style, was part of a second set of construction specifications produced in 1836.

Extant interior features original to the building include the groin vaults of the ceiling in the first-floor office spaces, plastered wall surfaces, molded wood service counters, and a built-in measuring device from 1859.

Late 19th century wainscoting composed of beaded vertical boards and wide baseboards survive in the first-floor corridor but the original pine flooring is covered with black-and-white marble tiles.

The main stair is modestly detailed with stone treads, wood handrail, and square iron balusters.