It would appear that despite the huge population growth over the decades, leading to more than 10,000,000 phones in many major cities (less than that actually, given phone exchange limitations and so on), nobody’s had the guts to change the (xxx) xxx-xxxx phone numbering system that’s been in action over there for the past 50 years. And apart from the issues with cities blowing the limit and getting multiple area codes, they’ve also got problems with cell-phones being tied to regions, rather than being truly nationally mobile.
In Australia we went through short-term pain for long-term gain, migrating from a phone numbering system that was mostly (xx) xxx-xxxx in the big cities (and a lot of variations in rural areas and for mobiles) to being uniformly (xx) xxxx-xxxx, which should allow for plenty of growth over several decades. Perhaps longer if fax machines and dialup modems (and separate lines for them) and even fixed-lines continue to die-off. It’s meant that dialling is pretty consistent.
On the other hand, it has to be pointed out that the North American numbering plan covers some 24 countries and territories, so I appreciate revamping it would be a helluva job.