This section includes various resources that I have found helpful for (predominantly US) economic history.
Data Sources
IPUMS - complete-count and samples from the US population census. Not all of the data from the manuscript census (for example, names) is available in the complete-count datasets, so I list a few additional datasets that complement the IPUMS data
Census Place Project - dataset constructed by Enrico Berkes, Ezra Karger, and Peter Nencka to capture sub-county locations.
Census Linking Project - dataset constructed by Ran Abramitzky, Leah Boustan, Katherine Eriksson, Santiago Pérez and Myera Rashid to allow researchers to link individuals across different census years.
NHGIS - resource for historical aggregate US data as well as GIS files
Ancestry - because the publicly available data from IPUMS does not include names, I often find Ancestry useful for searching for individuals. You may have access through your university library.
ICPSR - repository for thousands of datasets. I sometimes find the search function difficult to use when I don't know what I'm looking for
Historical, Demographic, Economic, and Social Data: The United States, 1790-2002 (ICPSR 2896) - collection of aggregate data from US Censuses
United States Agriculture Data, 1840 - 2012 (ICPSR 35206) - detailed aggregate data from US agricultural censuses
Agricultural and Demographic Records of 21,118 Rural Households Selected from the 1860 Manuscript Censuses (ICPSR 9117) - Bateman and Foust sample of households in 1860 in northern US from population and aggricultural censuses
Southern Agricultural Households in the United States, 1880 (ICPSR 9430) - Ransom and Sutch sample from the 1880 Census
Southern Farms Study, 1860 (ICPSR 7419) - Parker and Gallman sample from 1860 census
National Samples from the Census of Manufacturing: 1850, 1860, and 1870 (ICPSR 4048) - Atack, Bateman, and Weiss samples from Census of Manufacturing
United States Census of Manufactures, 1929-1935 (ICPSR 37114) - Vickers and Ziebarth samples from Census of Manufacturing
Prices and Wages by Decade - collection at the University of Missouri with detailed sources for historical price and wage data
Historical Transportation Maps - collected by Jeremy Atack. Includes maps of railroads, navigable rivers, and canals
Hathitrust - Incredibly detailed collection of historical publications. The search function is not always that accurate, so I often search using google instead.
R. R. Bowker's guide to State Publications - I have found this guide extremely useful for identifying possible data sources published in state documents.