Historian Robin Yonash has identified and organized dozens of online research resources that apply to Placer County, California, in general, with a primary focus on the towns in the Colfax, California, area.
These web sites cover the existing towns of Alta, Applegate, Colfax, Dutch Flat, Gold Run, Iowa Hill (AKA Iowa City until 1901), and Weimar. They also have information about the local historic towns of Bird’s Flat, Damascus, Elizabethtown, Humbug Canyon, Illinoistown, Monona Flat, New England Mills, Red Point, Succor/Sucker Flat, Towle, and Wisconsin Hill.
All of the following online resources are free to use unless otherwise indicated.
Genealogy/Family Tree Web Sites
Family Search to create a family tree (free)
My Heritage for research (subscription required)
Books on History — Online
History of Placer County, California, with illustrations and biographical sketches of its prominent men and pioneers, Thompson & West, 1882
Many of the these biographies have been transcribed and posted on the following web pages (ignore the county names at the top of the pages):
History of Placer and Nevada Counties California, with biographical sketches of the leading men and women, 1924
Business and Individual Directories
1884-5 McKenny’s Sacramento City & County Directory (includes Placer County–scroll down)
1888 California state gazetteer and business directory, by R. L. Polk & Co.
California Digital Newspaper Collection (The site describes itself as “A Freely Accessible Repository of Digitized California Newspapers from 1846 to the Present.”)
Elephind (limit your search using the options on the left; for example, there is an Iowa Hill in Australia)
Newspapers.com (subscription required)
California County Formation History (on the site, scroll down)
Placer County Parcel Maps with Township, Range, & Section (keep clicking on the number for area of the map you want to drill down to)
Census Records for the 1852 Special California Census–this is the Placer County portion.
Ancestry.com (subscription; two-week free trial available)
Family Search to create a family tree. Creating an account is free and gives you access to more tools.
My Heritage for research
Names of registered voters in Placer County in 1890 (in lieu of the missing 1890 Census) (index only; there is a small charge to obtain the actual copy of a death notice)
Index to births, 1852-1885 From the Placer Herald Newspaper, Auburn, California
(index only; there is a small charge to obtain the actual copy of a death notice)
Index to marriages, 1852-1885 From the Placer Herald Newspaper, Auburn, California