For many parents, one of the most important considerations when choosing where to live is the quality of the local school district. It is, however, very difficult to measure the quality and effectiveness of one school system over another, and state school systems vary in many ways.

A good state school system should excel in several aspects. A successful system should produce students who score well on aptitude tests, who are likely to graduate, and who tend to go on to college.

A state’s spending on its public school system is only one factor related to student success. While some state school systems with lower spending per pupil still compare favorably to systems in other states, most systems that rank high in student achievements also spend more per pupil. Across all states, public schools spend an average of $12,526 per pupil per year. In all but five of the 25 best ranking states, annual per pupil spending is higher than the national average.

While these are not absolutely critical, research shows that students with a strong foundation — in particularly gained by living with educated parents — are more likely to be enrolled in better-funded schools and are far more likely to be successful.

24/7 Wall St. reviewed data available from the U.S. Census Bureau, The National Assessment of Educational Progress, and the National Center for Education Statistics to create an index of all 50 state public school systems, from best to worst.

To identify the states with the best and worst schools, 24/7 Wall St. created an index inspired by the Quality Counts ranking of state education created by Education Week. We ranked the states based on a variety of measures that cover financial standing, academic achievement, and student chances for success. Graduation rate is derived from the Adjusted Cohort Graduation Rate (ACGR) for the 2015-2016 school year and comes from the National Center for Education Statistics (NCES). Per-pupil spending for the states for 2016 comes from the Census Bureau’s Secondary Education Finance data. Proficiency test results for math and reading comes from the National Assessment for Educational Progress (NAEP) and are as recent as 2017. Educational attainment and the percentage of non-low-income families came from the Census Bureau’s American Community Survey (ACS) and is for 2017 1-Year Estimates.

Click here to see the states with the best and worst schools.