WALTHAM — When the market first opened on Lexington Street, immigrants packed the aisles for a chance to dictate a letter to Lilian Rojas.
Many were too shy to say they could not read or write, so they whispered that they forgot their eyeglasses or some other excuse. The petite shop owner nodded and wrote all they wanted: love letters, Mother's Day cards, messages of longing and grief to deliver to relatives thousands of miles away.
Now, 17 years later, the number of immigrants in this city has soared. But the letter-writing lines at the small market near Waltham's city center have all but disappeared.
"It's incredible," Rojas said, standing amid the sacks of dry beans and pots of fresh tamales. "It's been a long time since someone asked for that."
A reason, researchers say, is that the latest waves of immigrants are far more educated than their forebears. Nearly 80 percent of the Massachusetts immigrants who arrived after 2000 have a high school diploma or some college education or a college degree, much higher than the 68 percent of those who came to the United States before 1980, according to an analysis of recent census figures by the University of Massachusetts Donahue Institute. The share of immigrants with a bachelor's degree or higher in Massachusetts has risen even more dramatically, from 26 percent among those who arrived before 1980 to 42 percent of those who came after 2000.
"Clearly our more recent immigrants are more highly educated than the immigrants in past decades," said Susan Strate, population estimates program manager at the Donahue Institute, based in Hadley. The data is from the American Community Survey, a nationwide survey, that covered the years 2007 to 2011 and applies to immigrants aged 25 and older.
Advocates for immigrants and researchers say the heated debate over immigration policy has tended to obscure public perceptions of immigrants' education levels, which have been slowly rising for years in Massachusetts and nationwide.
The trend is aided by an overall decline in the numbers of illegal immigrants, who tend to have less formal schooling. But immigrants' homelands have also built more schools, boosting literacy, and the United States has actively recruited high-skilled workers and college students from countries such as China, India, and Brazil.
The better educated workers are also changing the face of the economy, launching companies and creating jobs in Massachusetts and elsewhere in the United States, as well as changing the face of local schools and communities.
"Even though it's not been very widely recognized, the educational level of immigrants has risen all the way through since the 1980s," said Michael Fix, senior vice president of the Migration Policy Institute, a nonprofit that researches immigration. "Every decade it goes up."
Immigrants in Massachusetts are still less likely to have graduated high school than US-born residents; some 24 percent of foreign-born residents of Massachusetts do not have a high school diploma, compared with 8 percent of natives.
The percentage of immigrants who have advanced degrees, however, is now slightly higher than American-born residents — up to 18 percent compared with 16 percent of US natives in the state. Even illegal immigrants are arriving with higher levels of education.
Alan Clayton-Matthews, Northeastern professor, said he has witnessed firsthand one of the reasons why, in Santa María Tzejá, a remote village in Guatemala that saw brutal violence during the 36-year civil war. Townsfolk fled to the mountains and refugee camps in Mexico, but then in the 1990s returned to rebuild the town.
They also built new schools, with the help of the church Clayton-Matthews attends in Needham and other supporters. The village now has a middle school. Villagers and some outside supporters are now raising money for a high school.
"Now a lot of the immigration to the United States from this village is from kids who have either a middle-school education or a high-school education and are coming to the US to make money to support their other siblings," said Clayton-Matthews, an economist.
A prime exampl e was a man in Waltham on a recent day, scrolling through messages on his cellphone outside the market Rojas runs, known as Despensa Familiar . A 33-year-old laborer from Guatemala, he said he has only a sixth-grade education, but even that surpasses his father, a farmer back home. "My father did not go to school," said the laborer, who asked not to be named because he is here illegally. "He wanted me to learn to read and write so I wouldn't be like him."
Manuel Salazar, a 33-year-old landscaper in Waltham, said he studied psychology for three years at a university in Guatemala but moved north a few years ago because it became clear that he would earn more money. The cash he sends home pays for his daughter to attend one of the best private schools in Guatemala City.
"It's because of us that things are better there," he said.
Rojas, who immigrated legally from Guatemala, said the disappearance of her letter writing service was aided by automated computer services that enabled immigrants to send money home without her help. But it is also clear that people more often can read and write on their own.
She has seen the shifts in her own family. She attended high school in Guatemala but left to work and later moved to America and studied English and computers. She sent her children to good schools as she and her husband expanded the market into a distribution center for canned goods and fresh fruit and vegetables from Central America.
Rojas is a success in the community, but her daughter Monica, also an immigrant who came to America as a child, did even better in the United States. She was valedictorian of her high school class and the first in her family to earn a college degree. Rojas said her family's fortunes rose along with her customers'. "Thanks to them, we have done better," she said. "This is a country where you can overcome."