Which PBS anthology series aired Downton Abbey in the United States?

Masterpiece aired Downton Abbey in the United States as part of its PBS anthology programming. When the series premiered in America on 9 January 2011, it was presented under the Masterpiece Classic banner.

Masterpiece is PBS’s long-running showcase for acclaimed drama, mysteries and literary adaptations. Its history reaches back to 1971, when the programme launched as Masterpiece Theatre. The branding later expanded to include Masterpiece Classic and Masterpiece Mystery!

Downton Abbey was a particularly important success for the American strand. PBS supported the production with Britain’s ITV and broadcast the series with introductions by host Laura Linney. The US version also adjusted episode structures to fit American public-television scheduling and removed space originally used for British commercial breaks.

Viewers sometimes answer PBS because it was the broadcaster, but the question asks for the anthology series. PBS was the network; Masterpiece was the specific anthology presentation. That distinction makes Masterpiece the canonical answer.