The map shows the amount of oil on the coastline as reported each day by the federal government based on information from air and ground surveys. The amount of oil on portions of the coastline often changes from day to day because of many factors, including recent visits by cleanup teams or tides washing in new oil.

For the first month of the spill, the oil stayed mostly in the gulf. But in the last week of May, waves of oil began washing into Louisiana’s fragile wetlands and beaches. In June, oil landings began to be reported more frequently in the states to the east. Survey areas for Louisiana were first released on May 24 and for Mississippi, Alabama and Florida beginning on June 12. Survey data were not available for some days.