Union County, Oregon was formed from Baker County in 1864.
1870 Union County, Oregon Census
- Free 1870 Census Form for your Research
- Free 1870 Census Images and Index
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- Free 1870 Census Transcriptions
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- Hosted at Census Guide
1880 Union County, Oregon Census
- Free 1880 Census Form for your Research
- Free 1880 Census Transcription
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1890 Union County, Oregon Census
- Free 1890 Census Form for your Research
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1900 Union County, Oregon Census
- Free 1900 Census Form for your Research
- Free 1900 Census Images and Index
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1910 Union County, Oregon Census
- Free 1910 Census Form for your Research
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1920 Union County, Oregon Census
- Free 1920 Census Form for your Research
- Free 1920 Census Images and Index (partial)
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1930 Union County, Oregon Census
- Free 1930 Census Form for your Research
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- Hosted at Census Guide