town (township), Middlesex county, eastern Massachusetts, U.S. Sudbury lies along the Sudbury River, west of Boston, and includes the villages of Sudbury and South Sudbury. Settled in 1638 by Watertown residents and by English colonists, it was incorporated in 1639 and named for Sudbury, Suffolk, England. Present-day Sudbury has one of the wealthiest populations in the state. It is the site of a manufacturing and engineering laboratory for the defense contractor Raytheon (Raytheon Company).

In South Sudbury stands the restored Wayside Inn (c. 1705), which is the nation's oldest operating inn; it served as the setting for Henry Wadsworth Longfellow (Longfellow, Henry Wadsworth)'s Tales of a Wayside Inn (1863). The inn is the centrepiece of a restored 18th-century “village.” Great Meadows National Wildlife Refuge extends along the river through Sudbury. Inc. 1639. Area 25 square miles (65 square km). Pop. (1990) 14,358; (2000) 16,841.

city, seat of Sudbury district, southeastern Ontario, Canada, on Ramsey Lake, 40 miles (65 km) north of Georgian Bay of Lake Huron (Huron, Lake). It was named for Sudbury, Suffolk, England. Its settlement began with the location of a station of the new Canadian Pacific Railway (Canadian Pacific Railway Ltd.) on the site. Copper- and nickel-bearing ores were discovered there in 1883–84 during the railway's construction, and smelting operations got under way in 1888.

Sudbury became the most important mining centre in Canada, with a majority of its population employed in that industry. Huge nickel concentrators and smelters were erected at Copper Cliff (4 miles 【6 km】 west of the city) and at Falconbridge (12 miles 【19 km】 northeast). The city and the surrounding district still produce as much as one-fifth of all the nickel (nickel processing) mined in the world and almost all of Ontario's copper (copper processing). Significant amounts of gold, silver, platinum, cobalt, sulfur, and iron ore are also mined. Other industries include lumber milling, woodworking, machine shops, and brickworks.

Mining's importance in the city's economy began to decline in the 1960s relative to such sectors as health care, education, and public administration. Sudbury lies along the Trans-Canada Highway and two transcontinental railways and is the chief service and commercial centre for northern Ontario. It is the site of Laurentian University (1960) and Cambrian College (1966). Inc. town, 1893; city, 1930. Pop. (2006) metropolitan area, 158,258.

town (parish), Babergh district, administrative and historic county of Suffolk, England, on the River Stour. An important wool town during the Middle Ages, it has many half-timbered houses and three Perpendicular-style churches. Sudbury was first incorporated in 1554. As the worsted industry declined, silk weaving and coconut matting were introduced. Milling and brewing have also become important. The 18th-century English artist Thomas Gainsborough was born there in a house that is now an art centre. Pop. (2001) 20,188.