Low skilled manufacturing had already left the US by the early 1990s with stragglers leaving by the early 2000s.

Heck, I used to live in LA as a kid at that time in the 90s and 2000s and the sweatshops (yes we had sweatshops) sewing clothes for Gap were staffed by undocumented Mexican, Korean, Thai, Chinese, and Vietnamese migrants in the Fashion District.

On the other hand, even highly paid manufacturing segments like automotive had already normalized industrial robotics by the early 2000s [0].

Basically, income mobility was already dead by the 1990s [1]. The difference is most Boomer HNers were insulated by that because it is clear almost everyone on HN who grew up during that era grew up in a 50th percentile and above household back then and wasn't the head of a household in the 1980-2005 period.

[0] - https://unece.org/sites/default/files/datastore/fileadmin/DA...

[1] - https://www.congress.gov/crs-product/R44705