What was the first commercial radio station in the United States and which city did it broadcast from?
Answer: KDKA from Pittsburgh Pennsylvania
KDKA has described itself as the "Pioneer Broadcasting Station of the World", and traces its beginning — initially using the temporarily assigned "special amateur" call sign of 8ZZ — to its broadcast of the 1920 Harding-Cox presidential election results on the evening of November 2, 1920.
Although KDKA's history has been extensively reviewed, there are some inconsistencies between accounts, leading one researcher to note: "While the KDKA story is often recounted, the details tend to vary slightly both in the secondary source material and in the published recollections of the participants, including differences in the chronology of events and the relative importance of the parties involved."
For all intensive purposes, we'll consider good old KDKA the first commercial radio station in the US of A.