I didn't notice your reply otherwise I wouldn't have deleted my post. In my home town in northwestern MN there is an agricultural experiment station which paid $35,000 for a programming job a couple years ago. I made a spreadsheet and even as a single guy with my car paid off I'd only be able to save about $700 a month on that salary. And that's as a renter. Granted, heating costs are much more expensive in northwestern MN than they are in the south and a rental is a bit more expensive than $400. That said, if I had kids to support I would have had to live in a trailer park and would have qualified for food stamps.
I don't think that living in a rental and saving $700 a month is "solidly middle class" in the USA. Perhaps it is now, though, in a world of permanently diminished expectations.
You may be slightly out of touch if you think saving $700 a month is poor. Huge portions of America have no savings and live paycheck to paycheck. Many more have only a few hundred in savings total.
Not being able to save $700/month or to come up with $2,000 in an emergency situation in the USA is poor, no matter how much useless crap you bought with the rest of your money.
For some weird definition of "middle", I guess. "Middle class" is a designation without meaning, the kind of label that nearly everyone is eager to claim for themselves. Hardly anybody but the most indigent will admit they are poor, because in the US it's like admitting a moral failure. Otherwise you'd be middle class, just like everyone else.
Is the median $55k household in the US reasonably comfortable, able to have a family and buy a home without frequent financial stress over expenses like buying groceries, filling up the tank, or paying the water bill? If it's true that most Americans could not quickly produce $2000 in an emergency, I find that hard to believe. $55k DINKs are doing okay, but add a couple babies to the mix (not unreasonable for a "solidly middle class" family), and I think you're in for a rough time if you're saving for college and retirement like you ought.
I don't think that living in a rental and saving $700 a month is "solidly middle class" in the USA. Perhaps it is now, though, in a world of permanently diminished expectations.