As of 2015, the CDC website presents a color-coded map of the United States each week, which summarizes the flu outbreak level in each state. Outbreaks are categorized as either widespread, regional, local or sporadic. Any states that have no flu activity or do not report their status are identified.
The CDC flu map contains a link that alters the diagram, showing results from previous weeks. The map indicates only the geographic spread of influenza, not the severity of the breakout. Levels for Guam, Puerto Rico and the U.S. Virgin Islands are also included.
On another Web page, the CDC summarizes more extensive weekly information by region. States are divided into 10 categories, primarily by geographic location. A chart displays the number of sectors in each region that have regional or widespread flu activity during the week. It compares the number of outpatient visits for influenza-like illnesses to baselines and identifies the level, such as "Elevated."
The CDC's regional summary chart also reports the percentage of respiratory specimens that tested positive for influenza. National results are supplied weekly, while regions provide numbers for the most recent three weeks. The chart breaks down cases by the specific flu strain, such as A (H3) and A(H1N1)pdm09. Finally, the number of pediatric deaths is listed.