After President Barack Obama declared a federal emergency in Flint, Michigan, based on lead contamination of the city's water supply in January 2016, Reuters reporters MB Pell and Joshua Schneyer began an investigation of lead contamination nationwide with shocking results. In June 2016, they reported that although many states and Medicaid rules require blood lead tests for young children, millions of children were not being tested. In December 2016, they reported on the highly decentralized data they had been able to assemble from 21 states, showing that 2,606 census tracts and 278 zip codes across the United States had levels of lead poisoning more than double the rates found in Flint at the peak of its contamination crisis. Of those, 1,100 communities had lead contamination rates "at least four times higher" than Flint.