Verizon began building its LTE network back in 2010, and now it covers 99% of its CDMA footprint. Parkersburg, West Virginia gets the honor as the 500th market to get Verizon's LTE network, which now covers 298 million people, and that's an impressive figure considering there are only about 330 million in the country, and a fair portion of that number are children who probably don't need LTE service just yet.
Verizon has completed the buildout, but hasn't yet turned on LTE service in Alaska. That is expected to happen as soon as next month, and will mark Verizon being in all 50 states for the first time, because Alaska did not have Verizon coverage before.
Of course, completing the buildout is only one step of the process, because Verizon still needs to work on increasing network capacity in more densely populated areas like NYC. Verizon has confirmed that it is already working on those issues, and cites its newly acquired AWS spectrum as part of the solution there.