Before the Civil War, the United States saw the emergence of several new religious groups that lived in communes. Which one practiced "complex marriage" in which all men were married to all women in the group, and vice versa?

Before the Civil War, the United States saw the emergence of several new religious groups that lived in communes. The one that practiced "complex marriage" in which all men were married to all women in the group, and vice versa was the Oneida Community.

Explanation:

The Oneida Community was a social utopian religious community in Madison County, New York. It was founded in 1848 by John Humphrey Noyes and was finally dissolved in 1881. The writer Aldous Huxley, himself a follower of Noyes, described the Oneida community as follows:

"The Oneida community lasted for thirty years, and by all accounts, its members were exemplary citizens, unusually happy and far less neurotic than most of their Victorian contemporaries. Oneida's wives had been spared what one of Noyes's letter partners described as "the wretchedness of married life, as is generally in the world in vogue. The men saw their self-denial rewarded with a physical and spiritual experience that was deeper and more precious than that of unrestrained sexuality."

The Oneida Community Mansion House has survived to this day and was declared a National Historic Landmark in 1965. It continues today as a museum.