Short answer: you don't.
Longer answer: Having no geolocation capability whatsoever, your Mac has no idea where it is. Its location is that of the router to which it's connected.
Like your Mac, your router has geolocation capability and no idea where it is either. So how is your Mac's location known?
The answer is by correlating its location to iPhones that connect to your wireless router. Unlike routers and Macs, iPhones always know where they are. Those locations are collected and stored in a database Apple maintains and eventually updates. How long that takes is anyone's guess. At present, Apple still thinks your router is in the Chicago area.