Location Services allows apps like Maps, services like Spotlight Suggestions, and websites in Safari to gather and use data about your computer’s current location. Your Mac determines its approximate location using information from local Wi-Fi networks. Location Services collects the information in a manner that doesn’t personally identify you.
OS X Yosemite: Location Services
The locations is based on Apple's database. It appears that your Mac is using wifi network/router that Apple's database says is in Minneapolis, USA.
Apple updates their database based on info from iPhones (they have GPS).
The iPhone has to have turned on the option to send info to Apple. No one has found another way to get the location of a router added/corrected.
You can confirm that by going to well-know place with wifi
This is the Mac Pro desktop forum. I requested your post be moved to the MacBook Pro laptop forum.