The higher a state's child poverty rate, the worse that state performs on the National Assessment of Education Progress - or NAEP - a test given to samples of students in every state.

States like Massachusetts, Vermont and New Hampshire, with low child poverty rates, tend to outscore states like California, which has a larger population of low-income children. Nearly a quarter of California's children are English learners, and the majority of them are poor, contributing to the state's low NAEP scores. In 2013, 29.5 percent of California's 4th- and 8th- grade students scored proficient, compared with 52 percent in Massachusetts. Poverty rates do not reflect the higher cost of living in California.

Chart by John C. Osborn. Updated by Daniel J. Willis, Justin Allen and Yuxuan Xie

Note: Each year in the charts and graphs refers to both the calendar year and the fiscal year. Thus, 2013 incorporated data from the fiscal year 2013-14 (July 1 through June 30) as well as the calendar year 2013.