The political posturing over raising the minimum wage sometimes obscures the huge and growing number of low-wage workers it would affect. An estimated 27.8 million people would earn more money under the Democratic proposal to lift the hourly minimum from $7.25 today to $10.10 by 2016. And most of them do not fit the low-wage stereotype of a teenager with a summer job. Their average age is 35; most work full time; more than one-fourth are parents; and, on average, they earn half of their families’ total income.

None of that, however, has softened the hearts of opponents, including congressional Republicans and low-wage employers, notably restaurant owners and executives.

This is not a new debate. The minimum wage is a battlefield in a larger political fight between Democrats and Republicans — dating back to the New Deal legislation that instituted the first minimum wage in 1938 — over government’s role in the economy, over raw versus regulated capitalism, over corporate power versus public needs.

But the results of the wage debate are clear. Decades of research, facts and evidence show that increasing the minimum wage is vital to the economic security of tens of millions of Americans, and would be good for the weak economy. As Congress begins its own debate, here are answers to some basic questions about the need for an increase.