In Georgia, the 2 lane and 4 lane non-divided highways speed limit is 55 mph. On 4 lane divided highways it is 65 mph. On limited access highways like interstates, the speed limit is 70 mph. All of those are dropped 10 mph when in heavily populated areas, cities, or other less safe areas.
Now with that said, the state police do not routinely stop anyone unless they are at least 10 mph over the speed limit, or have other extenuating circumstances. Local police are prevented by law from routinely issuing tickets for less than 10 mph over the posted speed limit in order to minimize speed traps designed strictly to generate ticket revenue. Therefore, in practice, almost everyone drives at least 10 mph over the speed limit, and many stretch that to 20+.
Our license points system does not kick in until +14 mph above the speed limit. In other words, a ticket at 10 mph over the speed limit only costs you the one time price of the ticket, does not affect your driving record, and does not affect your insurance costs. Above 14 mph above the speed limit, i.e. 15 mph and up, results in points on your license, increased ticket costs, and increased insurance costs that stick with you for at least 3 years. The points, ticket costs, and insurance ramifications escalate as the speed goes up. If you receive too many points, your license will be suspended, and insurance costs are based on total points accumulated over the last 3 years, and apply to all vehicles that you own.
On our interstates, you will be the slowest person on the road at 70 mph. You will be passed often at 80 mph, but will also pass some. Once you reach 90 mph, you will still be passed occasionally but not often, and will pass almost everyone else, but the speed differential will be relatively small.
I personally set my cruise control at either 10 or 14 mph over the posted speed limit depending on whether I am in a hurry or not. If I am in an emergency, or extreme hurry, then posted speed limits are irrelevant, and I drive at the limit of my personal comfort level for risk. This varies from only slightly over the posted speed limit in congested, or high traffic areas, or highly policed areas, to well over 100 mph on straight open roads with good visibility and light or no traffic. Regardless of all that, I just love to twist the throttle when on a bike, any bike, or floor it in a sports car, any sports car, and almost always have to slow back down to cruising speed after going through the gears, sometimes by a lot.