| Zip Code : | 61341 |
| City : | Marseilles city, Ottawa city, Seneca village |
| County : | LaSalle County |
| State : | Illinois (IL) |
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| Land Area : | 90.89 sq mi |
| Water Area : | 3.93 sq mi |
| Latitude : | 41.3520416 |
| Longitude : | -88.6932814 |
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| Population (2010): | 8,234 |
| Population Estimate (2012) : | 7,877 |
| Population Density : | 90.60/sq mi |
| Housing Units (2012) : | 3,656 |
| Median Household Income (2012) : | $49,871 (Illinois : $56,853, USA : $53,046) |
| Median Family Income (2012) : | $67,407 (Illinois : $70,144, USA : $64,585) |
| Median House Price (2012) : | $135,200 (Illinois : $190,800, USA : $181,400) |