The poverty rate in the US is about 13% [1]; we would expect those people to not have any savings. That leaves about 33% unaccounted for. It looks like 42% of workers in the US make less than $15/hr [2], which does fit the figure fairly close. However, some of those are teenagers, so they don't count as they aren't living on their own.
I'd like to see some analysis of spending. How many people don't have any savings because they aren't spending wisely. This girl [3] discovered that she could actually save for a deposit for a house in London, despite making under £40k (about $53k). That's less than the median US income and presumably doesn't go all that for in London. She was simply spending a lot of money on food, drinks, and specialty coffee.
[1] https://poverty.ucdavis.edu/faq/what-current-poverty-rate-un...
[2] http://fortune.com/2015/04/13/who-makes-15-per-hour/
[3] https://www.theguardian.com/money/2018/jan/29/can-you-really...