Log Into your Google+ Local Business Listing account, Edit Listing and scroll down. A quarter of the way down on the left hand side you will see a field form for the Service Areas and Location Settings for your Local Business. Click the radial button so it is marked yes and it will open up the rest of the form as you see in the picture on the left.
Next mark the Distance from one Location field and where it says Service Area within [ 100 ] <---put in the number of how many miles your business is willing to cover for it's service area, for example I put in 100 miles which covers three states and multiple cities as I live Close to the Arizona, Nevada and California state lines that covers multiple cities like Bullhead City AZ, Las Vegas & Laughlin NV as well Needles California.
If there is a incorrect location it also allows you to fix the marker for exact location and service areas for your local business as you see in the picture to the right.
Using the Service Area and Location Settings form on Google+ Local is really beneficial for multiple cities and towns especially if you live in a compact area like Los Angles that has Anaheim, Escondido, Huntington Beach, San Diego and More. I use this Local Strategy for my local Business clients and they continually rank high for their niche listings in the Organic and Local rankings