Mercer County, Pennsylvania

Founding: 1803 (declared in 1800)
Parent county: Allegheny

Namesake: Hugh Mercer, Continental Army general
Seat: Mercer (1804–)

Land area: 673 square miles

Population (2020): 110,652

Population (historic): 3,228 (1800); 32,873 (1840); 49,977 (1870); 57,387 (1900); 99,246 (1930)

Periods of population growth: pre-1800–1880; 1890–1960

Subdivisions: Three cities; 14 boroughs; two CDPs; 31 townships

Pre-1940 residences (estimated): 13,885 (26.6%)
Pre-1940 housing survival rate: 60.2%
Pre-1860 housing survival rate (1940): 17.7%

Farm housing in disrepair (1950): 11.6%

Nonfarm housing in disrepair (1950): 6.2%
Average farmhouse value (1930): $1,847
Average outbuilding value (1930): $1,470
Average farmhouse size (1940): 6.8 rooms
Number of farms (1920): 4,499
Average farm size (1920): 54.6 acres
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Mercer

Namesake: Hugh Mercer, Continental Army general

Founding: 1803 (platting); 1805 (post office); 1814 (incorporation)

Population (2020): 1,982

Population (historic): 781 (1840); 1,249 (1860); 2,344 (1880); 1,804 (1900); 2,125 (1930)

Periods of population growth: pre-1840–1860; 1870s; 1900s; 1920–1960
Pre-1940 residences (estimated): 401 (41.3%)
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