WASHINGTON — Senator Barack Obama won his 11th straight nominating contest on Thursday, carrying the Democrats Abroad global primary by a 2-to-1 margin over Senator Hillary Rodham Clinton and prevailing among American expatriates in every region of the world.

The results represented thousands of ballots submitted from Americans in 164 countries and territories from Feb. 5 to 12.

The overseas Democrats were allocating a small number of delegates –­ 4.5 — on Thursday, under a proportional system that allotted 2.5 to Obama and 2 to Clinton. A further 2.5 will be determined at a Democrats Abroad convention on April 12 in Vancouver, Canada. The group also holds 4 superdelegate votes, for a total of 11 votes at the national convention in late August in Denver.

But in a close contest, Democrats Abroad said they felt particularly engaged.

Democrats Abroad for the first time allowed votes to be cast online, though others were cast by mail, fax or in person, and they came in “from Antarctica to Zambia ­– from A to Z,” said Christine Schon Marques, the group’s international chair, in a phone interview from Geneva. “Many people overseas are very concerned about the war in Iraq; they’re looking for change.”

One of the Antarctica voters was Adam Lutchansky, a 26-year-old Alaska native who just finished a six-month stint working in the power plant at McMurdo Station and voted via the Internet.

“We only get mail service six months out of the year and it takes about a month for a letter to make a round trip to the U.S.,” he said by e-mail message, “but even here in Antarctica we have a dependable Internet connection. It was great to finally see a political body get onboard with the security and flexibility of the Internet.”

By way of comparison, Mr. Obama’s global 66-to-33 percent lead over Mrs. Clinton was nearly identical to the edge he recorded in states like Minnesota, or his home state of Illinois.

Mr. Obama won by strong majorities in every region and nearly every country. The senator, who was born in Hawaii, did particularly well in the Asia-Pacific region, winning 79 percent of the vote in Japan and 76 percent in Indonesia, where he lived as a youth. He also did well in Europe, carrying more than 70 percent of the vote in France and Switzerland.

Mrs. Clinton won in Israel, the Dominican Republic and the Philippines. Her best regional showing was in the Americas, with 44 percent of the vote.

Republicans do not hold a global primary. They cast votes directly in their home districts, as overseas Democrats also have the option of doing.