Nathaniel Pitcher Tallmadge was an American lawyer and politician. He served two terms as United States Senator from New York (1833–1844) and was the 3rd Governor of the Wisconsin Territory (1844–1845).

The Territory of Wisconsin was an organized and incorporated territory of the United States that existed from July 3, 1836, until May 29, 1848, when an eastern portion of the territory was admitted to the Union as the State of Wisconsin. Belmont was initially chosen as the capital of the territory. In 1837, the territorial legislature met in Burlington, just north of the Skunk River on the Mississippi, which became part of the Iowa Territory in 1838. In that year, 1838, the territorial capital of Wisconsin was moved to Madison.