Sprint Spark Band 41 Carrier Aggregation is now active in over three dozen markets across the US. S4GRU broke down the news after a Sprint employee leaked an internal announcement onto Reddit. The blog, which exclusively covers Sprint 4G rollouts (yes, you can write about anything on the Internet), provides lists of the supported cities and devices.
Early test markets included Atlanta, Chicago, Detroit, and Houston. Thirty-five more cities have joined in time for the initial launch.
Carrier Aggregation is the first step of implementing LTE Advanced, offering higher peak data rates and a better experience for everyone overall. Things get pretty technical, but here's more of a breakdown if you're curious. 2x Carrier Aggregation, in this instance, refers to the ability to connect to two LTE Band 41 carriers simultaneously.
For now, the Galaxy S6, S6 Edge, and Note Edge are the three Samsung devices capable of utilizing the network enhancements. LG has the G4 and G Flex 2. HTC has the M9. Lastly, there is the ZTE Hot Spot.
You can get more hyper-specific Sprint information from S4GRU at the source link below.