Sprint has added six more large cities to its “Spark” high speed data service: Fort Lauderdale, Houston, Austin, Dallas, Fort Worth, and San Antonio. Sprint claims that Spark delivers wireless peak data speeds of up to 50 to 60 Mbps. And if you have any doubts about that, Sprint has already achieved blindingly fast speeds of 1.3Gbps in lab tests, so the carrier believes it won’t be a stretch to eventually offer up to 2Gbps over-the-air with potential future updates.

In addition to the six new cities, Sprint Spark has already been deployed in New York, Chicago, Miami, Tampa, and Los Angeles. Sprint plans to deploy Sprint Spark in about 100 cities during the next three years, with 100 million Americans living in coverage areas over the end of this year.

Sprint says the faster speeds are possible because of its upgrades to its older 3G network to its newer 4G LTE network.  Sprint is redeploying its 800MHz spectrum for LTE and 3G, delivering improved in-building coverage for voice and data. Sprint expects the network rollout to be largely complete by mid-2014.

The faster network speeds and tri-band devices will also be available to customers of Sprint’s no-contract services Boost Mobile and Virgin Mobile USA, where the Sprint Spark network is available.

To access the higher speeds with Sprint Spark, customers will need Sprint-ready devices that support its tri-band enhanced LTE technology, which enables the devices to shift from one wireless band to another, depending on such factors as location or type of application.

So far, the only smartphone that supports Sprint Spark tri-band is the new HTC One Max, but Sprint says the Samsung Galaxy S4 mini and Samsung Galaxy Mega will soon get over-the-air (OTA) updates that will also support the network-switching technology.  A few mobile hotspot devices also already support the technology, including the Netgear Zing, Netgear 341U USB Modem, and Novatel MiFi 500 LTE.

Virgin Mobile’s first Spark-compatible device will be the Netgear Mingle, a mobile hotspot  that Sprint says will be available this quarter on Virgin Mobile’s Broadband2Go no-contract plans. Broadband2Go includes daily service on Sprint’s 3G and 4G networks for $5 per day, or per month at $25 for 1.5GB of data or $55 for 6GB of data.