What weights to use with American Community Survey data?

I want to aggregate ACS data to get county and MSA estimates. What weights should I use? And are there any other problems I need to take care of?

First, I would recommend looking at the NHGIS project, as it has ACS data aggregated at multiple geographic levels.

If the information you are looking for is not available through NHGIS, the multi-year samples of the ACS are appropriately weighted as a representative sample of the U.S. population and are ideal for studying smaller populations such as counties and MSAs. The weights you would use in this case would be the same as for any other analysis. You can read a little about the wieghts on the IPUMS-USA FAQ page.

I hope this helps.

Thank you! Your answer is very helpful.