Johnson Chair Co. - Swivel Desk Chair  

I recently bought this old chair and as far as I can tell it's from the 40's or 50's but I'm not really as I'm an amateur in this realm. I'd love to get some more information on the chair and see if I could identify where and when it was made. It's a beautiful piece that I would love to learn more about. 

The maker is easily visible, printed on two parts of the chair just saying Johnson Chair Co. 

On the back of the chair there is also a number stamped in yellow reading 18629. I'm assuming this is a serial number or possible a date stamp but I'm not sure. 

Any insight would be greatly appreciated.