Ltbewr, you are correct. Both
UA and
F9 have daily nonstops from
LGA to
DEN, which--as I mentioned above--is a unique exception to the general 1500-mile rule.
You are also correct about same-plane service. Many flights from
LGA to destinations within 1500 miles continue on to cities beyond the perimeter. For example,
AUS falls just outside the perimeter, making nonstop flights impossible, but
AA operates two daily flights that stop in
HOU, just inside the perimeter, in order to circumvent the rule.
If memory serves,
HP applied to the DOT not too long ago for an exemption allowing it to serve
PHX nonstop from
LGA. Its argument seemed fairly reasonable: almost every other hub & spoke airline in the U.S.--even
F9, thanks to the
DEN exemption--is able to serve
LGA from its primary hub, so why shouldn't
HP be allowed to do the same from
PHX. However, as far as I know nothing ever came of that.
Perhaps if NY, like DC, had powerful politicians wanting convenient flights from a close-in airport to their home cities (McCain, I'm looking at YOU!),
LGA would have perimeter rule exemptions like
DCA does. But alas, we don't, and so we don't.
Common sense is not so common. -Voltaire