C# mysql 75 mile radius map covering the entire US

I have a database full of zipcodes and their lat/long. What i want to do is to be able to cover the entire US in 75 mile radius circles with as little overlap as possible. Any hints or tips? My intentions are to cover the entire US in 75 mile circles with as little overlap as possible, ess开发者_开发技巧entially i want to know all zipcodes that are 150 miles from each other starting in the middle of the country towards the coasts.

What i'm trying to say is I need to make sure that I have 75 mile circles cover the entire US, essentially that I can not miss any zipcodes. So if i started in Kansas and I moved out, I would have 75 mile circles overlapping maybe in 10 miles increments until all of the us in covered.

Kind of like this map http://modernsurvivalblog.com/pictures/usa-survival-location-map-300-mile-zones-not-safe-with-population-more-than-100-thousand-1433x975.jpg

However, that map does radius's around 100k population. I want to just start at a specific lat/long and cover the entire US.

Off the top of my head, you can try overlaying the map with a square grid with each grid square being 106 miles by 106 miles. Then create your circles based on the center of the grid square with your 75 mile radius which should be very close to the vertices of the square intersecting the perimeter of the circle. I don't know if this will give you the absolute minimum overlap but is a starting point that provides 100% coverage of the area.