Their departure signalled the start of the US missionary movement, and today the United States sends more Christian missionaries abroad than any other country, experts say.
The United States sent out 127,000 of the world's estimated 400,000 missionaries abroad in 2010, according to Todd Johnson, director of the Centre for the Study of Global Christianity at Gordon-Conwell Theological Seminary in Massachusetts.
In distant second place is Brazil, which sent 34,000 missionaries abroad in 2010, he said.
The United States receives the most missionaries as well, with 32,400 in 2010, he said. Many are Brazilians - Catholic, Protestants and Pentecostals - who largely work in Brazilian communities in the Northeast, Johnson said.
Two of the original American missionaries — Adoniram Judson and his wife Ann Hasseltine Judson — settled in Burma, the Southeast Asian country now known as Myanmar, where Adoniram Judson remained for decades and translated the Bible into the local language.
The Judsons defied expectations that the group would never return, coming home to the United States before leaving again. But he died at sea, and she succumbed to smallpox and spotted fever in Burma.
Roughly half of the original group and their families died at sea or abroad.
Christians credit Judson and his wife with laying the foundations of the American missionary tradition and this month held events in Massachusetts, from lectures to tours of historic sites, to mark the 200th anniversary of the couple's four-month sea journey in 1812.
Christians in Myanmar hope to celebrate the anniversary of the arrival of the Judsons next year, organisers said.
Historic departure of first US missionaries re-enacted
At a reenactment on Monday of the Judsons' departure from Salem Harbor, once a thriving seaport, about 60 people gathered to watch as actors dressed in period costumes spoke of leaving on a foreign mission, perhaps for the rest of their lives.
The actors, wearing black hats and long coats, waved farewell before walking along a wharf toward the harbour.
In the audience was Maung Htwe, 44, pastor of the Overseas Burmese Christian Fellowship church in Allston, Massachusetts who grew up in Yangon, Myanmar. He said many Burmese people know about Judson because he translated a Burmese-English dictionary that is still in use.
There are 1.5 million Baptists in Myanmar today, "so that gives you a sense for the importance of that sailing and the pattern that he set for missionaries to follow down through the ages," said Dexter Bishop, a representative of the Adoniram Judson Baptist Association.
At the time the Judsons left Salem, thousands of European missionaries had already fanned out across the globe, working to promote Christianity among native populations under the auspices of colonial powers, Johnson said.
The role of missionaries has changed dramatically since the Judsons' time, he said, and missionaries today tend to work independently or through organisations not affiliated with churches that traditionally ran missionary agencies.
And their work may be focused on providing humanitarian aid rather than founding churches and winning converts. Some mission groups question whether to send missionaries to developing countries at all, Johnson said.
"There are still streams within Christian missions that are suspicious of all preaching, or suspicious of all social action," he said.
After World War II, many newly independent countries declared moratoriums on western missionaries, and independent missionaries became more prevalent, said Dana Robert, author of "Christian Mission: How Christianity Became a World Religion."
Humanitarian work became common, and churches in the 1940s started large nongovernmental organizations, she said.
By 2000, about two-thirds of the world's Christians came from countries where western missionaries worked a century earlier, and there was an explosion of interest in mission work among Christians from Asia, Africa and Latin America, according to Robert.
With the increasing globalisation of communications and transportation, there has been an exponential increase of short-term volunteer missions, Robert said.
"The current situation is almost a total free-for-all," she said. "Somebody sitting at home with an Internet connection can virtually set up a mission." — Reuters