http://money.cnn.com/2018/05/17/news/economy/us-middle-class-basics-study/index.html [cnn.com]
"Nearly 51 million households don't earn enough to afford a monthly budget that includes housing, food, child care, health care, transportation and a cell phone, according to a study released Thursday by the United Way ALICE Project. That's 43% of households in the United States."
See also: https://www.forbes.com/sites/noahkirsch/2017/11/09/the-3-richest-americans-hold-more-wealth-than-bottom-50-of-country-study-finds/ [forbes.com]