In 1996 Boston ranked twenty-second in population among cities in the United States, with a population of 558,394, down 2.8 percent since the 1990 census when its residents numbered 574,283 (48 percent male, 52 percent female). The 1997 population for Boston's five-city New England County Metropolitan Area (NECMA), spanning both Massachusetts and New Hampshire, was 5.83 million, up from 5.69 million as of the 1990 census. Boston's population is projected to pass 600,000 by 2010 when a population of 6.5 million is projected for the NECMA.

Boston's original settlers were mostly of English origin and formed the basis of the city's old aristocracy, known as the "Boston Brahmins." By the middle of the nineteenth century, the first waves of Irish immigration began, made up largely of peasants fleeing the potato famine in that country. The Irish eventually became one of the city's major ethnic groups and gained a dominant position in its political life. The first Irish mayor of Boston was elected in 1885. In 1960 the scion of two prominent Boston Irish political families—John Fitzgerald Kennedy (1917–1963)—was elected president of the United States. In spite of the city's original Puritan roots, nineteenth-century waves of Irish, Italian, and French-Canadian immigration made Boston a strongly Catholic city. Today more than half the city's population is Catholic—the third-largest percentage of any city in the United States.

Escaped slaves arrived in Boston during the Civil War era via the Underground Railroad. In the 1970s, 1980s, and 1990s, Boston's Hispanic and Asian American populations grew. Many immigrants are drawn to the region by its educational institutions and high-technology jobs.

City Fact Comparison
Indicator Boston Cairo Rome Beijing
(United States) (Egypt) (Italy) (China)
Population of urban area1 2,915,000 10,772,000 2,688,000 12,033,000
Date the city was founded 1630 AD 969 753 BC 723 BC
Daily costs to visit the city2
Hotel (single occupancy) $192 $193 $172 $129
Meals (breakfast, lunch, dinner) $44 $56 $59 $62
Incidentals (laundry, dry cleaning, etc.) $26 $14 $15 $16
Total daily costs (hotel, meals, incidentals) $238 $173 $246 $207
Major Newspapers3
Number of newspapers serving the city 3 13 20 11
Largest newspaper The Boston Globe Akhbar El Yom/Al Akhbar La Repubblica Renmin Ribao
Circulation of largest newspaper 470,825 1,159,450 754,930 3,000,000
Date largest newspaper was established 1872 1944 1976 1948
1United Nations population estimates for the year 2000.
2The maximum amount the U.S. Government reimburses its employees for business travel. The lodging portion of the allowance is based on the cost for a single room at a moderately-priced hotel. The meal portion is based on the costs of an average breakfast, lunch, and dinner including taxes, service charges, and customary tips. Incidental travel expenses include such things as laundry and dry cleaning.
3David Maddux, ed. Editor&Publisher International Year Book. New York: The Editor&Publisher Company, 1999.

Boston is also home to a sizable Jewish community, which accounts for the single largest distinct religious denomination after the Catholics. Two other religions have their headquarters in Boston: the Unitarian-Universalist Association and the First Church of Christ, Scientist, founded in the city in 1894 by Mary Baker Eddy (1821–1910). An imposing modern Christian Science complex, including a school, library, and worship facilities, was completed in the early 1970s.

Boston skyline along the Charles River. ()