Here's how much money you need to earn to be in the top 1% in your 30s

Income inequality has been growing in America for decades.

As the country's richest get even richer and the share of people below the poverty line increases, America's middle class has been gradually disappearing.

One of the most striking ways to view that income gap is to look at how much money it takes to be in the top 1% of income earners in your 30s.

The age group is roughly a decade into their careers, and any gap that might have existed right after college has had many years to expand.

Consider this chart, which shows the rapid rise.

To create the chart, Business Insider analyzed data from the 2015 American Community Survey, an annual survey by the US Census Bureau that interviews about 1% of all US households about various economic, demographic, social, and housing characteristics.

The resulting breakdown shows that median incomes grow by just $10,000 (or 25%) between 30- and 39-year-olds, while top-1% income jumps from $173,000 to $419,000 over the same age range. That's a 142% increase.

The increases among people in their 30s are much greater than people in their mid- to late-20s. Someone who's 25 needs an income of $116,000 to be in the top 1%. A 29-year-old needs to make $160,000.

This approach has its limits. Surveys like the ACS don't capture everyone at the top, like celebrities and financiers, and some researchers prefer to use alternate forms of data, such as tax records, when studying those at the top of the income and wealth distributions.

What it can do is offer a window into the compounding effects of wealth. Having more disposable income enables people to save and invest more than if they have significantly less. As a result, the rich tend to get richer while people toward the middle tend to survive on their salaries alone.