Roll over each state to see which five EHR vendors account for the most attestations in each state, eligible hospitals and eligible physicians combined. Each state is color-coded by the most prevalent vendor in that state. Color saturation reflects the percentage of the state attesting the number one top vendor, with darker colors representing a higher percentage of the attestations in the state.

Eight distinct vendors emerge as the leading vendor in at least one state. Epic Systems Corp. holds the top spot in the greatest number of states, with a total of 24. Cerner Corp. is second to Epic, with half of their total -- a number that could rise with their recent $1.3 billion acquisition of Siemens Health Services. Allscripts Healthcare Solutions Inc. and eClincalWorks LLC are the top vendors in seven and three states respectively. Utah has far and away the largest single-vendor concentration in any one state, with 87.2% of EHR systems -- combined EHs and EPs -- provided by Intermountain Healthcare.

Some important notes about the data shown above: