What mainstream denominations (if any) hold a Young Earth Creationist view? As the title asks, which mainstream denominations hold a YEC View?
Typically, any congregation professing the YEC viewpoint are going to be non denominational. Though the name implies there is an unspecified disagreement among non denominational churches, the vast majority are biblical litetalists. This means they will naturally take the YEC view.

As Mawia pointed out in a comment, the date of the creation, and even the very process, is considered a matter of opinion in most denominations and not a doctrine.

Specifically, 7th Day Adventists are biblical literalists and therefore young earth creationists. They are the only denomination that I know of that explicitly holds that view.



Considering their shared roots with 7th Day Adventism, some think that Jehovah's Witnesses are Young Earth Creationists. Instead, it seems they are not. They are Progressive Creationists, which is a variety of Old Earth Creationism that excludes Evolution.