How north and south zone is decided

So, I was talking with a buddy about how I hunt in Hondo south of 90 and have a couple more weeks of deer season. They live in Karnes County and end this week. I havent been able to figure out how where I am in Hondo is considered south and yet he is noth zone. So, what is the line that determines noth and south during deer season????

It goes by county. Even though they are south of you, they are also significantly east of you. The "South Zone" could be more accurately described as "Southwest"

Well they actually have muzzleloader season 1/6-1/19, so he can still hunt.