Adjacent counties

• Allen County - north
• Hardin County - east
• Logan County - southeast
• Shelby County - south
• Mercer County - west
• Van Wert County - northwest

2000 census

As of the census^[16] of 2000, there were 46,611 people, 17,376 households, and 12,771 families residing in the county. The population density was 116 inhabitants per square mile (45/km²). There were 18,470 housing units at an average density of 46 units per square mile (18/km²). The racial makeup of the county was 98.12% White, 0.24% Black or African American, 0.18% Native American, 0.41% Asian, 0.03% Pacific Islander, 0.20% from other races, and 0.83% from two or more races. 0.67% of the population were Hispanic or Latino of any race. 59.5% were of German, 10.9% American, 6.9% Irish and 6.3% English ancestry according to Census 2000. 97.9% spoke English and 1.2% Spanish as their first language.

There were 17,376 households, out of which 35.30% had children under the age of 18 living with them, 62.10% were married couples living together, 7.80% had a female householder with no husband present, and 26.50% were non-families. 23.30% of all households were made up of individuals, and 10.50% had someone living alone who was 65 years of age or older. The average household size was 2.62 and the average family size was 3.11.

In the county, the population was spread out, with 27.60% under the age of 18, 7.80% from 18 to 24, 28.20% from 25 to 44, 22.00% from 45 to 64, and 14.40% who were 65 years of age or older. The median age was 36 years. For every 100 females, there were 96.50 males. For every 100 females age 18 and over, there were 93.10 males.

The median income for a household in the county was $43,367, and the median income for a family was $50,024. Males had a median income of $37,024 versus $23,809 for females. The per capita income for the county was $19,593. About 4.90% of families and 6.20% of the population were below the poverty line, including 7.20% of those under age 18 and 6.40% of those age 65 or over.

2010 census

As of the 2010 United States Census, there were 45,949 people, 17,972 households, and 12,749 families residing in the county.^[17] The population density was 114.5 inhabitants per square mile (44.2/km²). There were 19,585 housing units at an average density of 48.8 units per square mile (18.8 units/km²).^[18] The racial makeup of the county was 97.8% white, 0.4% Asian, 0.3% black or African American, 0.2% American Indian, 0.3% from other races, and 0.9% from two or more races. Those of Hispanic or Latino origin made up 1.2% of the population.^[17] In terms of ancestry, 53.0% were German, 12.6% were Irish, 8.9% were American, and 8.0% were English.^[19]

Of the 17,972 households, 32.8% had children under the age of 18 living with them, 57.9% were married couples living together, 8.5% had a female householder with no husband present, 29.1% were non-families, and 25.3% of all households were made up of individuals. The average household size was 2.53 and the average family size was 3.02. The median age was 40.0 years.^[17]

The median income for a household in the county was $52,018 and the median income for a family was $60,318. Males had a median income of $44,267 versus $30,591 for females. The per capita income for the county was $25,290. About 5.8% of families and 7.2% of the population were below the poverty line, including 9.5% of those under age 18 and 4.6% of those age 65 or over.^[20]

Courthouse

The county's first courthouse, built in 1851 for $11,499, was in use until 1894, when the current courthouse opened. Occupying an entire city block, the courthouse and its adjacent powerhouse cost $259,481. Some 85 men took 18 months to construct it, starting on July 2, 1893. Built of Berea sandstone with tile floors, the courthouse was highly fire-resistant. The boilers for heating and power generation, a significant cause of fire at the time, were in a separate powerhouse. Steam-driven dynamos produced the electricity that, along with steam for heating and hot water, was fed to the building via an underground conduit. The courthouse marked its centennial in 1994, and remains the seat of the county's courts,^[22] along with the much newer West Municipal Court in St. Marys.^[23]

Cities

• Saint Marys
• Wapakoneta (county seat)

Villages

Townships

Census-designated places

• New Hampshire
• Saint Johns
• Uniopolis

Unincorporated communities