The definition of America's "middle class" can vary wildly depending on who you ask. For some, it's defined by certain attributes: If you're hardworking, thrifty and humble, for example, you're middle-class. For others, it means earning a substantial salary but not so much that you'd be considered rich.
Northwestern Mutual's 2018 Planning & Progress Study found that 88 percent of Americans believe annual income is the defining factor of the middle class, although 65 percent said that lifestyle and perspective also play a key role.
Just over 50 percent of survey respondents said that earning an annual salary of, or owning assets of, between $50,000 and $99,999 qualifies a household as middle-class, whereas 26 percent said $1 to $49,999.
Another 20 percent said the middle class is composed of those earning or possessing between $100,000 and $499,999.