Loop through a folder and all subfolders in Powershell

Hey Scripting Guys,

I found this Powershell command online:

ls -r  *.txt  | % {(gc $_ | % { $_.TrimEnd() }) | sc $_ }

to remove trailing spaces from the end of each line of each text file in a folder.  How can I make it loop through the folder and all of its subfolders?

Thanks.