We recently heard from Motorola Senior Director of Software Development David Schuster that the company was working on testing and rolling out Android 5.1 Lollipop to the Moto X (2nd gen) and Moto E LTE, and sure enough it appears that U.S. Cellular customers should see the update hit their devices pretty soon.
According to an Android software page on U.S. Cellular’s website, the build number for Lollipop on the 2nd generation Moto X is LPE23.32-21 while for the Moto E LTE it is LPI23.29-15. Since this is an over-the-air update you’ll need to be connected to WiFi to download the software update. To check if the update is available for your device yet, open the Settings app, select About Phone, and then System Updates. If it’s rolled out to you then you’ll see information about the update and be able to begin the installation process from this screen.