Where is the Chocolatey installation path?

There is an environment variable set on installation, ChocolateyInstall, which is set to C:\Chocolatey by default in versions of Chocolatey less than 0.9.8.27. After that, this defaults to C:\ProgramData\Chocolatey.

NOTE: By default, the C:\ProgramData folder on Windows is hidden. You will either need to enable hidden files and folders through Folder Options | View or you can navigate directly to the path shown above by copy/pasting directly into the Windows Explorer address bar.

In version 0.9.9 of Chocolatey, it actively moves from the old folder location to the new one.

You can also pre-emptively create this environment variable before installing Chocolatey to control where it gets installed if required.