Is there a single source with the land area of each PUMA? I tried downloading a .dat.tar file from IPUMS but it would not work on my computer.
Files from IPUMS NHGIS should have a .dat.gz or .csv.gz extension. Previous versions of the NHGIS website included directions for combining files into a .tar file, but these are no longer applicable. We have a number of resources and video tutorials on working with the NHGIS extract system available.
PUMA shapefiles from NHGIS contain an AREALAND attribute that will tell you the land area for each PUMA; they can be downloaded through the NHGIS Data Finder page. If you are an R user, example exercises are available (specifically NHGIS for R - Exercise 1 and NHGIS for R - Exercise 2) to practice working with shapefiles in R in order to extract the information you need.