They are more likely to be working teenagers (about half of minimum-wage earners are younger than 25), they are slightly more likely to be women, and they often have never married.

The highest proportion of workers earning the federal minimum wage of $5.15 an hour or less are those in service occupations, such as food preparers and servers.

Still, for low-wage workers such as Alice Laguerre, 53, of Orlando, earning enough to pay for such basics as food and utilities can be a struggle.

"I always wanted to go to college," says Laguerre, who dropped out of high school in the ninth grade and later obtained her General Education Development (GED) certificate. She has worked in the service industry for about 15 years.

"But I smile every day," she says. "When I’m by myself, I cry. People never know when I’m down and out. Times are very hard."

While the federal minimum wage hasn’t changed since 1997, grass-roots efforts to boost the hourly rate have led more states to raise the wage on their own. About 20 states now have minimum wages that are above the federal level. A bill passed last week and expected to be signed by California Gov. Arnold Schwarzenegger will raise that state’s minimum wage over two years from $6.75 to $8 an hour, the highest in any state.

Since September 1997, the purchasing power of the minimum wage has deteriorated by 20%. After adjusting for inflation, the value of the minimum wage is at its lowest since 1955, according to the Center on Budget and Policy Priorities, a policy organization focused on low- and moderate-income families and individuals.

Organizations such as the National Federation of Independent Business are opposed to raising the minimum wage. They say most businesses already pay well above the federal level and that the free market, not a government mandate, should determine employee wages.

Meanwhile, other labor groups, such as the AFL-CIO, are actively campaigning for a wage increase. The AFL-CIO is lobbying members of the U.S. House of Representatives and Senate, and the labor organization has backed legislation or ballot initiatives in 19 states to raise state minimum wages.