Brigham Young died in 1877. Around that time, the U.S. government made polygamy against the law. Polygamy had been practiced by Young and some members of the church since the 1840s. Laws by the U.S. government led to many Latter-day Saints leaders going into hiding, and many polygamists being sent to jail. In 1890, the church stopped polygamy. This is thought to be the beginning of the modern era of the Mormon church.