It is not a regional problem. It is AT&T and those ISP's that use AT&T as their transport (Mediacom, for example) that is the problem. You need to complain to your ISP about this.
Here is one more test. There is no WEB page at this IP address, but it is an active server and it is in the same Class C our WEB server is in.
Ping 70.85.193.17
I am will to bet, those of you who cannot reach our WEB and Wiki pages (70.85.193.18) can ping the above address.