Nicolaus Allgeier was the first Euro-American to settle in the town of Nicolaus, which is named for him. He was born in Freiburg, Germany, in 1807, and came to the eastern United States around 1830. He worked as a trapper for the Hudson Bay Company, traveling overland to California in 1840. The following year, he was hired by John Sutter to help build an adobe house located about one and a half miles below Sutter's Hock Farm—the first Euro-American settlement in Sutter County. The road between Sutter's new adobe house and his Sacramento land (where he was planning to build Sutter's Fort) crossed the Feather River at the place now called Nicolaus, so Sutter needed someone stationed there with a ferry. In 1842, when the construction of his adobe house was completed, Sutter therefore deeded to Allgeier one square mile of land (then valued at $400) in what is now Nicolaus, in payment for Allgeier's past and future labor, with the agreement that Allgeier would ferry Sutter across the river regularly.
Allgeier constructed a hut from willow poles and covered it with tule grass and dirt, following the style in which Nisenan homes were built. He built a ferry in a similar manner and hired American Indians to row Sutter across the river whenever it was not convenient for Allgeier to do so himself. Allgeier lived in this hut until 1847, when he built an adobe house on the same square mile of land. In 1849 he opened a hotel, and in 1850 he sold over 300 lots of the land to start a town here.