The Arab population in the United States has nearly doubled in the past two decades, the Census Bureau's first report on the group shows.
Experts cited liberalised US immigration laws and unrest in the Middle East as reasons that made many people come to America.
The bureau counted nearly 1.2 million Arabs in the United States in 2000, compared with 860,000 in 1990 and 610,000 in 1980. About 60% trace their ancestry to three countries: Lebanon, Syria and Egypt.
The census report stops at 2000, so there is no data to measure the impact of the attacks of 11 September 2001.
But tighter immigration procedures imposed after that have reduced the flow of Arabs to the United States.
While earlier Arab immigrants came from countries with large Christian populations, newer arrivals are from heavily Muslim countries such as Iraq and Yemen.
"Immigrants from the Arab world come for the same reason all immigrants come - economic opportunity, opportunities to have an education, to develop a professional career," said Helen Samhan, executive director of the Arab American Institute Foundation, a research group.
"The fact that immigration procedures and visa applications have been so tightly screened is going to slow down the volume of new Arab immigrants"
Arab American Institute Foundation
Samhan said the lifting of US immigration quotas in the 1960s opened the door to people from Arab countries and many took advantage during the 1980s and 1990s, with a large number coming from nations such as Lebanon and Iraq where there were wars.
Five key states
Almost half of the Arabs in the United States live in five states - California (190,890), New York (120,370), Michigan (115,284), New Jersey (71,770) and Florida (77,461).
"It would be better to come to America than Europe or Canada," said Zak Trad, 33, of Anaheim, California, who came from Lebanon three years ago. "It's the largest Arab community not in an Arab country. I didn't think I would be a stranger here."
New York City, the first stop for millions of immigrants for more than a century, had the largest Arab population among US cities, 69,985.
The 9/11 backlash helped to get
US Arabs involved in politics
The Detroit suburb of Dearborn, Michigan, where many Arabs first settled to work in the automobile industry, was next at 29,181.
Sterling Heights, Michigan, was the city with the largest percentage of Arab-Americans, 3.7%, followed by Jersey City, New Jersey, with 2.8%. Dearborn's population is about 30% Arab, but it was not ranked because the Census Bureau only counted cities with at least 100,000 residents; Dearborn has about 98,000.
The Census Bureau asked those who received the long version of their decennial questionnaire to list their ancestry. The form was sent to about one-sixth of all households.
Arab-Americans say their population is larger than that reported by the Census Bureau, but many are reluctant to fill out government forms because they came from countries with oppressive regimes.
The Arab American Institute Foundation said that just over 15,000 visas were issued to immigrants from Arab countries in 2002, compared with more than 21,000 in 2001.
"The fact that immigration procedures and visa applications have been so tightly screened is going to slow down the volume of new immigrants," Samhan said.
"These days, anything that moves votes one way or another by the thousands can have an impact of seismic proportions"
"The scrutiny that will be placed on immigrants from Arab and Muslim countries is going to be even greater than other places."
The backlash against Arab Americans following Sept 11 served to draw them closer and get more involved in politics.
The concentration of Arab-Americans in a few states that are key to presidential elections next autumn, particularly Michigan, also has boosted their political influence.
In October, seven of the eight Democratic presidential candidates attended the Arab American Institute's national leadership conference in Dearborn, as did the heads of the Democratic and Republican parties.
"These days, anything that moves votes one way or another by the thousands can have an impact of seismic proportions," said pollster John Zogby, himself an Arab-American.