Union County

Berkeley Heights Township [1809: New Providence to 1951]
Clark Township [1864]
Cranford Township [1871]
ELIZABETH city [1693: Township to 1855, also borough 1740-1855 (coterminous with Township from 1790)]- county courthouse
Fanwood borough [1895]
Garwood borough [1903]
Hillside Township [1913]
Kenilworth borough [1907]
Linden city [1925: created through merger of Linden borough (1882) and Linden Township (1861)]
Mountainside borough [1895]
New Providence borough [1899]
Plainfield city [1858: village to 1869 (later added Plainfield Township, 1847-1878)]
Rahway city [1858 (later added Rahway Township, 1804-1861)]
Roselle borough [1894]
Roselle Park borough [1901]
Scotch Plains Township [1878: Fanwood to 1917]
Springfield Township [1794]
Summit city [1869: Township to 1899]
Union Township [1808]
Westfield town [1794: Township to 1903]
Winfield Township [1941]

Source:  New Jersey Localities: Civil Divisions and Municipalities; http://www.thegreenpapers.com/slg/localities.phtml?state=NJ