The upper middle class has become the largest income group in the United States, according to new research, even as the cost of living in major metropolitan areas continues to climb.

The shift represents a significant change in America's economic landscape, with more households moving up the income ladder rather than falling into lower brackets. This trend suggests economic mobility has enabled families to achieve higher earnings over time.

However, rising living costs are offsetting some of these income gains, particularly in expensive urban markets. In New York City, families now need to earn more than $125,000 annually to afford living in any of the city's five boroughs, highlighting the persistent challenge of housing affordability.

The research indicates that while America's traditional middle class is shrinking, the primary driver is upward mobility rather than economic decline. More households are achieving upper middle-class status, which typically includes professional occupations and higher educational attainment.

The findings reflect broader economic trends where income growth has occurred alongside significant increases in housing and living costs, particularly in major metropolitan areas. This dynamic creates a complex picture where household incomes are rising but purchasing power may not be improving proportionally in high-cost markets.