I'd be curious what you would have defined as 'poor' in the early 1970s. In 1972, the U.S. poverty threshold for a nonfarm family of four was $4,275. We were a family of 5 and below that level. We were eligible for food stamps and Medicaid. It was likely irresponsible for my grandparents to take that one annual trip to Disney for the sake of the kids, but they did it anyway, even if it meant sacrificing other things like clothes and presents. When they decided to move from NJ to FL, they fell for a 'cheap land' scam buying into a drained swamp on the edge of the Everglades with small cheap houses built on a dirt road with no city water service. By sheer luck, sticking it out, the nearby cities to the east expanded over the decades, ultimately spreading to unincorporated county land and paving the roads, bringing in public service and water/sewer, and putting their house officially in 'city limits', raising the home values - though both grandparents only had social security and veteran's benefits from my grandfather's service in WWII.
But I'll concede the point that we were 'middle class' since it seems to be bringing up some resistance and contention. It's not what I would call middle class, but if that's what people think is middle class today, I guess my view is skewed. I am happy to not be there myself, and hope I never have to fall to that level of middle class-ness.