5-28-13 Bluemustang Josh & Pyroscott: I was vacationing in the valley last month & noticed a few locations in Harlingen that were receiving 4G LTE signal. It was primarily near US 77 & US 83. I use the Sensorly app (available for free in the Google play store) to track LTE coverage & it does a fine job of doing just that. It also has a speed test built in which I find gives a better representation of the true download/upload speed rather than peak speeds when tested with Speedtest.net
When you install the app, you can see the areas in Harlingen where I was able to get LTE signal. You can also view it from a PC here: http://www.sensorly.com/map/4G/US/USA/Sprint/lte_310sprint
So LTE across the valley may not be that far off!
Paul