I’m working on a paper on income inequality and would like to have income inequality by county for the entire US. There are older papers that have used this and referenced the Census
I'd like county level GINI coefficients or other income inequality measures at the county level from 2000-2010
IPUMS NHGIS provides tabulated US Census data on a wide variety of topics. One such topic is income inequality. Using the IPUMS NHGIS data finder, you’ll be able to find many tables (with GIS boundary codes) that provide information on the GINI index at various geographic levels.
I hope this helps and you find what you are looking for. Let us know if you have any further questions.