Bronx, New York
In 1898 the five boroughs consolidated into New York City. Each borough's border matches its county's border. This Wiki lists the most data about these at the county level except Brooklyn.
1664 Yorkshire became the first large government unit (not actually a county) organized by New York after the English took control from the Netherlands. It was divided into three ridings including North Riding (Westchester, Bronx, New York (Manhattan), Nassau and part of Queens counties). 
1683 New York extinguished Yorkshire. What later became the Bronx was then created part of Westchester County from part of Yorkshire. 
1874 The West Bronx was annexed to New York County. 
1895 Areas east of the Bronx River were annexed to New York County. 
1898 What became the five boroughs were consolidated into New York City, and her county governments were dissolved. The Bronx joined New York City attached to Manhattan.
1914 Bronx was separated from Manhattan. Bronx borough/county borders are the same. 
City Clerk's Office
Supreme Court Building
851 Grand Concourse
Bronx, NY 10451
Official Bronx Historian
Dr. Lloyd Ultan
3309 Bainbridge Avenue
Bronx, NY 10467
- Wikipedia contributors, "York Shire (Province of New York)" in Wikipedia: the Free Encyclopedia at http://en.wikipedia.org/wiki/York_Shire_(Province_of_New_York) (accessed 16 December 2011).
- Kathryn Ford Thorne, New York Atlas of Historical County Boundaries (New York: Simon and Schuster, 1993), 118-19. At various libraries (WorldCat); FHL Book 974.7 E7t.
- Wikipedia contributors , "The Bronx" in Wikipedia: the Free Encyclopedia at http://en.wikipedia.org/wiki/The_Bronx (accessed 4 January 2012).
- Elizabeth Petty Bentley, Genealogist's Address Book: State and Local Resources, with Special Resources Including Ethnic and Religious Organizations, 6th ed. (Baltimore, Md.: Genealogical Pub., 2009), 374-75. At various libraries (WorldCat); FHL Book 973 D24ben 2009.