Was the ownership of slavery was permitted west 120 W longitude?

Yes, the ownership of slavery was permitted west of 120° W longitude, particularly in the territories acquired by the United States after the Mexican-American War. The Compromise of 1850 allowed for the possibility of slavery in these new territories, despite ongoing debates about the expansion of slavery. However, the Kansas-Nebraska Act of 1854 further complicated the issue by allowing residents of those territories to decide the legality of slavery through popular sovereignty. Ultimately, tensions over slavery in these areas contributed to the events leading up to the Civil War.