The middle class is cracking, but if you want a statistic that "proves" this, there isn't one. The cracking isn't a statistic, it's the culmination of observations logged over the past 15 years about these critical measures of what it takes to qualify as middle class:

1. How much income a household needs to secure the minimum qualifications of a middle class standard of living / quality of life, based on the conventional standards of the 1960s - 1980s. (The qualifying characteristics are listed below.)

2. The upward or downward mobility of those claiming middle class status. Put another way: if it requires monumental effort and perfect execution to achieve the minimum qualifications of middle class security, then that isn't a "middle class" set of qualifications, that's an elite set of qualifications.

3. Precarity: how much (or little) financial disruption does it take to tip a household into a down-spiral that becomes increasingly difficult to escape. The foundation of any non-trivial definition of "middle class" (any definition that is solely based on income is trivial) is the financial resilience offered by ownership of assets, particularly income-producing assets, and savings that can be tapped to handle emergencies.

I've been addressing these issues for many years. Here are a few of my posts on the decay of the middle class:

Priced Out of the Middle Class (June 28, 2012)

What Does It Take To Be Middle Class? (December 5, 2013)

Misplaced Pride: Most of the "Middle Class" Is Actually Working Class (June 14, 2019)

Squeezed for Decades, America's Working Class Is Finally Up Against the Wall (May 13, 2024)

Here are the minimum requirements to qualify as middle class, drawn up by myself and readers:

1. Meaningful healthcare insurance. By meaningful I mean healthcare insurance that doesn't have high deductibles--if you have to pay thousands of dollars before the insurance kicks in, that's not insurance, it's a simulation of insurance--and insurance that isn't reduced to meaninglessness by limitations on coverage and/or zero coverge for core elements of healthcare.

2. Significant equity (25%-50%) in a home or other real estate.

3. Income/expenses that enable the household to save at least 6% of its net income.

4. Significant retirement funds: 401Ks, IRAs, etc.

5. The ability to service all debt and expenses over the medium-term if one of the primary household wage-earners lose their job.