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The 2000 Census showed that Mercer County had a population of 120,293 people. This represented 0.98% of the total population of Pennsylvania, making it the state's 29th most populous county (out of 67 counties).

From the Census Estimates for 2009<1>, Mercer had a population of 116,071 people. This is a decrease of 3.51% since the 2000 Census.

The following table shows the recent changes in population. Other than 2000, the population counts have been estimated by the Census Bureau.

Since 2000
Year-to-Year Change
2010116,638-3.04%+0.49% since 2009
2009116,071-3.51%-0.5% since 2008
2008116,660-3.02%-0.4% since 2007
2007117,133-2.63%-0.35% since 2006
2006117,540-2.29%-0.46% since 2005
2005118,084-1.84%-0.53% since 2004
2004118,708-1.32%-0.34% since 2003
2003119,117-0.98%-0.16% since 2002
2002119,310-0.82%-0.37% since 2001
2001119,756-0.45%-0.45% since 2000
2000120,293The Last Census

Mercer County had 49,859 Housing Units<2> at the time of the 2000 Census.

The 2000 Census shows that Mercer County has a total area<3> of 682 square miles [1,767 km²]. Of this total, 671 square miles [1,739 km²] of the area is land, with the balance (1.58%) being water (10.76 square miles [27.86 km²]).

Using the above population and land area values, Mercer County had a population density of 179.1 people per square mile [69.1 people/km²], making it the state's 29th most densely populated county (out of 67 counties).

US Census QuickFacts

The Census Bureau has created documents containing demographic information that are called QuickFacts. A QuickFact that is specific to Mercer County is available. The QuickFact also contains a comparison between Mercer and the state of Pennsylvania.

Click here for the Mercer County QuickFact (QF-42085).

Below are some of the communities that are located in Mercer County:

(2009 Est)
(2000 Census)
Change in
Grove CityQF-42316567,6658,024-4.47%

Below are the counties that adjoin and form the boundaries of Mercer County. A link to their specific Census QuickFact has been provided.

(2009 Est.)
(2000 Census)
Change in
Mahoning (OH)QF-39099   SW236,735257,555-8.08%
Trumbull (OH)QF-39155   W210,157225,116-6.65%
ButlerQF-42019   SE184,694174,0836.1%
CrawfordQF-42039   N88,52190,366-2.04%
LawrenceQF-42073   S90,16094,643-4.74%
VenangoQF-42121   E54,18357,565-5.88%

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U.S. Census Bureau
Census QuickFact for Mercer County

Footnotes ...

<1>On a yearly basis, the US Census Bureau creates an estimate of the county's population. Keep in mind that this is an estimate and not an actual count. The last physical count was the 2000 Census and the next count will be for the 2010 Census.

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<2>A Housing Unit is a broad term for those places where people live (whether occupied or temporarily vacant), such as a house, an apartment, a mobile home, or an area that is considered as a separate living quarter. Separate living quarters (consisting of one or more rooms) are considered to be those places where people live, sleep and eat separately from others and that have access to the outside (either directly or by a shared hallway).

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<3>The area value has been supplied by the US Census Bureau and it can be different than the geographic boundaries of Mercer. The value given by the Census Bureau reflects their statistical (or sampling) requirements.

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<4>All Quarter-dollar coin images from the United States Mint.

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