The recent debate about splits vs. overlays has made we wonder what proportion of people in each NANP country live in places that still allow local calls to be dialed without specifying an area code. Resources such as
Actually, we do know the answer for most NPA countries: Jamaica and the Dominican Republic are both completely overlaid, so presumably 100 percent of their populations must dial with 10D or 1+10D. Conversely, none of the remaining island members of the NANP have more than one NPA each, so they probably all still support 7D dialing. Canada is now almost completely overlaid. As far as I can see, the only remaining Canadian NPAs without a current or planned overlay are 807 in northwestern Ontario and 867 spanning the three territories. Both of those regions are sparsely populated, so close to 100 percent of Canadians will live in non-7D areas by 2024 (by which time the overlays planned for NPAs 506 and 709 will be active).
The leaves the US. There are plenty of overlays, but also lots of remaining singleton area codes. There is no obvious pattern: some very populous cities (e.g., Detroit and Jacksonville) remain un-overlaid, along with predominantly rural or tiny single-NPA states such as Alaska, Hawaii, Wyoming, Montana, both Dakotas, Delaware, Rhode Island, Vermont, New Hampshire and Maine. Conversely, although most major metropolitan areas now have overlays, there are also plenty of rural overlay examples, such as western Kentucky, northern Wisconsin and the entire states of Idaho and West Virginia. The driving factor is when an older NPA happened to require relief; no geographic splits have occurred in the past decade, meaning that all relief NPAs introduced since then have been overlays. In the decade or so prior to the last geographic split (575 splitting from New Mexico's 505 in
2007), many new area codes were introduced, and different state preferences dictated which form of relief (split or overlay) was used. For instance, California's PUC was slower to embrace overlays than many other states, which is why there are still so many singleton NPAs (some of them geographically quite tiny) in the Golden State.So can anyone hazard an estimate about what fraction of the US population still has the ability to dial 7D calls?
Bob Goudreau Cary, NC (in the 919/984 overlay)