As high-speed LTE services roll out across the US, many are wondering when their neighborhood will benefit. The iPhone app Coverage (US$2.99) produces zoomable maps that detail 2G, 3G, 4G and LTE coverage across all four major US cellular providers: AT&T, Verizon, Sprint and, for those willing to unlock their iPhones, T-Mobile.

The maps are stored locally, so a data connection isn't necessary. I used it to explore my Arizona neighborhood, the East Coast and West Coast. My first impression is that broad LTE coverage is still restricted to the biggest cities, and Verizon is clearly way out in front. AT&T is significantly behind (though working on it), and Sprint and T-Mobile are barely players. That's likely to change as time goes on, and the app will keep the maps updated.

I think Coverage is most useful in two ways. First, it could help those considering a purchase based on LTE availability. Second, travelers will like to know what to expect at their destination.

Using the overlays and switching one type of coverage on and off, or comparing carrier maps is really helpful.

Coverage runs as a universal app on all iOS devices running iOS 5 or greater and is highly recommended. You can see some example maps in the gallery.

This article was originally published on Tuaw.