Joni Hersch, a law and economics professor at Vanderbilt University, looked at a government survey of 2,084 legal immigrants to the United States from around the world and found that those with the lightest skin earned an average of 8 percent to 15 percent more than similar immigrants with much darker skin.
"On average, being one shade lighter has about the same effect as having an additional year of education," Hersch said.
The study also found that taller immigrants earn more than shorter ones, with an extra inch of height associated with a 1 percent increase in income.
Other researchers said the findings are consistent with other studies on color and point to a skin-tone prejudice that goes beyond race.
Hersch took into consideration other factors that could affect wages, such as English-language proficiency, education, occupation, race or country of origin, and found that skin tone still seemed to make a difference in earnings.
That means that if two similar immigrants from Bangladesh, for example, came to the United States at the same time, with the same occupation and ability to speak English, the lighter-skinned immigrant would make more money on average.
"I thought that once we controlled for race and nationality, I expected the difference to go away, but even with people from the same country, the same race — skin color really matters," she said, "and height."
Although many cultures show a bias toward lighter skin, Hersch said her analysis shows that the skin-color advantage was not due to preferential treatment for light-skinned people in their country of origin. The bias, she said, occurs in the U.S.
Economics professor Shelley White-Means of the University of Tennessee at Memphis said the study adds to the growing body of evidence that there is a "preference for whiteness" in America that goes beyond race.
Hersch drew her data from a 2003 federal survey of nearly 8,600 new immigrants. The survey used an 11-point scale for measuring skin tone, in which 0 represents an absence of color and 10 the darkest possible skin tone.
From those nearly 8,600 participants, she focused on the more than 2,000 who were working and whose skin tone had been recorded during face-to-face interviews.
William Darity Jr., an economics professor at the University of North Carolina, said Hersch's findings are similar to a study he co-authored last year on skin tone and wages among blacks.
"We estimate that dark- or medium-skinned blacks suffered a discriminatory penalty of anywhere from 10 percent to 15 percent relative to whites," he said. "This suggests people cue into appearance and draw inferences about capabilities and skills based on how they look."
Darity said it is not clear whether the bias is conscious or subconscious.
Hersch said her findings, which will be presented at the annual meeting of the American Association for the Advancement of Science next month in San Francisco, could support discrimination lawsuits based not on race, but on color.
"There are very few color discrimination suits, but they are on the rise," she said. "But these suits can be hard to prove."