[MarkMc]

> American's used to be able to support large families of 4+ kids with only 1 working parent. Now you have households with both working and they can't afford to have kids.

This statement isn't supported by the Pew Research article you linked to. If real average earnings are constant then a household which now has two breadwinners will double its income and be better off.

Also keep in mind longitudinal effects: native-born Americans have seen their wages rise but this is offset by immigrants who generally have lower-than-average wages - but still higher than in the country they emigrated from. Both groups are better off even though average wages haven't changed.