It's more or less been in schism since our own "modernist-fundamentalist" controversy that started in the early 20th century and really culminated in the 1970s. So a schism in American lutheranism already happened.
Basically you have two types of lutheran bodies in America, conservative (confessional) synods and liberal (non confessional) synods. The former believes in the lutheran confessions where the latter believes they are "still up for interpretation" which is just modernism (our teachings can change with time).
ELCA is the biggest one and is liberal and pozzed. like 99.9% of the time when you see "lutherans" doing dumb things in the media it is them.
LCMS and WELS are pretty solid, there are only a few minor differences in things like church governance but they are both historically "lutheran" in their theology.
Alot of the synods aren't even in theological disagreement, but are only separated by cultural history, like ELS is a Norwegian immigrant synod, There is a Tennessee synod as well.
Most of them are in communion with each other.
t. LCMS member