The study measured 2015 data from the private Population Reference Bureau on the topics of economic well-being, education, health, and family and community.
Top states for overall child well-being were New Hampshire, Massachusetts, Vermont and Minnesota, with Iowa and Connecticut tied for fifth place.
The five worst states for overall child well-being were Arizona, Nevada, Louisiana, New Mexico and, at the bottom of the list for the second year in a row, Mississippi.
The report also pointed out national findings such as how the number of families living in high-poverty neighborhoods has risen slightly over the past decade. In Arizona, Louisiana, Mississippi and New Mexico, at least 20% of children lived in high-poverty neighborhoods in 2015 as was the case in 2010 to 2014, according to the report.
The Annie E. Casey Foundation is a nonprofit group focused on improving the well-being of American children. Laura Speer, co-director of the study and associate director of policy reform and advocacy for the foundation, said she was most surprised by improvements in the high school graduation rate (with 83% graduating on time in 2014/2015, up 1 percentage point from 2012/2013) and the teen birth rate: 22 births per 1,000 girls in 2015, down from 24 in 2014.
"They had been at historically good levels, and both the high school dropout rate and the teen birth rate continued to drop this year," Speer said. "And they're now at the lowest levels they've ever been."
The states ranked highest on the child well-being list tended to be in the Northeast or upper Midwest, while the ones ranked lowest were in the South or Southwest. Speer said a big reason for these rankings had to do with each state's approach toward children's health care.
"There were a few states in there that didn't take advantage of Medicaid expansion," she said. 'They didn't take advantage of the opportunities that the government provided over the past five years."
Other states had huge improvements in child health-care coverage. Between 2010 and 2015, California had a 67% decline in uninsured children, the highest in that time period. Colorado, Minnesota, Nevada, New Mexico, Oregon and South Carolina also had declines of over 50%, according to the report.
Speer said future health-care provisions may have an impact on the progress that has been made surrounding children's coverage.
"We definitely think that the gains we have made over the 10 or 15 years in covering kids and families are potentially at risk with the proposals that have been discussed by the president and congress," she said. "There's little doubt that there will be negative repercussions, especially for low-income familes."
President Donald Trump's proposed budget
would cut the Children's Health Insurance Program by at least 20%, as well as Medicaid, which covers millions more kids.
"Kids are about almost half of all the enrollees in Medicaid, so kids would be disproportionately harmed there," said Bruce Lesley, president of First Focus, a nonpartisan advocacy organization for children and family policy issues. "And what we're talking about there is kids who are either poor or disabled, so you're really hitting the most vulnerable kids in society."
Speer said she feels optimistic and hopes policy-makers will be thinking deeply about the potential implications of their decisions on not only health insurance coverage but the various state programs that provide family support.
"This is not a time to step back from these gains. We should be proud of them and we should maintain them," she said. "I'm hopeful that policy-makers will hold the line on the gains we've made so far and will make the decisions to protect these kids and families."