Why did Transcendentalism became an important cultural and literary movement?

Because it is one of the pioneer movements that advocated the initiation of social reforms.

Explanation:

In that context, transcendentalists are important because they advocated for greater rights for women and the abolition of slavery. It is important to emphasize that the movement was formed in the United States even before the American Civil War outbreak. The transcendentalists aspired to freedom; they nurtured truth and knowledge. They advocated education for all because it is a way for people to express their abilities and thus be socially useful in general. Women were also involved in the movement, and some have left a deep mark in histories such as Margaret Fuller and Elizabeth Palmer Peabody.

i would say that the politicial parties from state to state varies.