Does rsync use encription also for local tranfers?

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Hy everybody,
I'm using rsync to backup/synchronize folders to/from USB connected external hard drives.
But I can't find an answer to a doubt.
Does rsync use encription also for local tranfers?
For "local transfer" I mean a transfer that doesn't go through a network like
folders synchronization with external hard drives.
I'm asking because the speed of local transfers doesn't seem quite good for an USB 2.0 connected hard drive.

Thanks for your help.