I'm looking for a data set of US citizens/residents, etc. With data on things such as age, geographic location, gender, income, marital status, etc. The more the better. Where can I find an appropriate set of data? A sample population made up of individuals.
Integrated Public Use Microdata Series (IPUMS USA) is a pretty amazing data source. It is one of the largest public tools for individual level data in the world. It allows you to extract data from previous census years as well as across census years. Many many variable choices are available including
age, geographic location, gender, income, marital status as well as many others.
State voter files are a source for data about residents who have registered to vote. This data gives name, address, age, and sometimes more (like party affiliation) for millions of people. Economic demographics would have to be infered by matching to census blocks.
For example, the Ohio Secretary of State site hosts data here:
Not all states have public voter data, for example, the state of Wisconsin.