Here's a report that summarizes the cellphone carriers' deployment of LTE service in USA. LTE (Long Term Evolution) provides faster speeds of data download, typically between 10 and 20 megabits/second, although some lightly used LTE networks are even faster.
http://www.fiercewireless.com/special-reports/progress-report-snapshot-us-lte-deployments-2013
Scroll down to see LTE maps from the four major cell service providers.
http://www.fiercewireless.com/special-reports/progress-report-snapshot-us-lte-deployments-2013
Scroll down to see LTE maps from the four major cell service providers.