Move Photos App and data to external drive to make room on main drive I am trying to make space on my Mac. It's overloaded and slow. I wanted to know if I can remove my photo application with all it's data and store it on an external drive? I understand that I couldn't access it if the external drive was not connected to my Mac. 

Can I do this? 

I have a MacBook Pro running Sierra (10.12.3).
All you have to do is move it.


Plug in your external drive
Copy (click and drag) your Photos library from your internal drive to your external drive
When complete, hold down the Option key and launch Photos.
In Photos, select Photos > Preferences, and in the General tab, click Use as System Photo Library.
Once you have confirmed that the library is there and is working, delete your old library off your internal drive