How do I change the default library path for R packages

Windows 7/10: If your C:\Program Files (or wherever R is installed) is blocked for writing, as mine is, then you’ll get frustrated editing RProfile.site (as I did). As specified in the accepted answer, I updated R_LIBS_USER and it worked. However, even after reading the fine manual several times and extensive searching, it took me several hours to do this. In the spirit of saving someone else time…

Let’s assume you want your packages to reside in C:\R\Library:

1. Create the folder C:\R\Library. Next I need to add this folder to the R_LIBS_USER path:
2. Click Start –> Control Panel –> User Accounts –> Change my environmental variables
3. The Environmental Variables window pops up. If you see R_LIBS_USER, highlight it and click Edit. Otherwise click New. Both actions open a window with fields for Variable and Value.
4. In my case, R_LIBS_USER was already there, and Value was a path to my desktop. I added to the path the folder that I created, separated by semicolon. C:\R\Library;C:\Users\Eric.Krantz\Desktop\R stuff\Packages.

(NOTE: In the last step, I could have removed the path to the Desktop location and simply left C:\R\Library).