is it possible to RUN mac OS X (preferably 10.11 el capitan) ON a usb drive?

i would like to know if it is possible to RUN mac OS X (preferably el capitan) ON a usb drive. i am not talking about installation usb drive to install mac OS X on my computer, i am talking about installing mac OS X ON a usb drive and run mac OS X FROM THAT usb drive, with the usb drive acting like a hard drive, a place for mac OS X to store all it's files, and have the computer's CPU, GPU, RAM, etc... do all the computing. basically ruing mac OS X whenever i boot with the usb plugged in and run windows whenever i boot with the usb plugged in. this has been done chrome OS before (actually it's the open source Chromium OS) and i would like to know if the same thing could be done for mac OS X. of course, speed and storage might be a problem, but to me, that's not. Storage is not a problem and read/write speed can be pretty fast since i use USB 3.0

please help me with this