Number Crunching: Introducing the State Charter Growth Index

Given major differences in state size, I was curious which states were doing well on charter growth when controlling for their populations.

I played around with state numbers for total new school charter growth and net charter growth (growth minus closures), and then compared these numbers to overall state population.

From there, I converted (schools / state population) into an index.

See results below with two caveats: (1) I don’t think new school numbers are totally clean (2) I was doing a lot copying and pasting in excel and I might have made mistakes.

Let me know if my math is wrong and I will fix the sheets.

High Growth States: 25+ on Growth Index or 20+ on Net Index 

Yes, somewhat arbitrary cut offs, but anyways…

For 2015, the major (proportional) drivers of new school development were: DC, DE, AR, TN, RI, AZ, CO.

For 2015, the major (proportional) drivers of net new school development were: DE, TN, RI, NH, AR.


I was surprised to see Delaware, Rhode Island, and Arkansas do so well. Yes, they are small states. But still…

Also interesting to see Michigan and Ohio having negative charter school growth given that everyone always complains about loose authorizing in these states.


New York, Pennsylvania, and Illinois are really doing poorly, reflecting, it seems, the weak charter growth in New York City, Philadelphia, and Chicago. The politics in the more left learning big cities remains pretty brutal.

That being said, New York had 18% enrollment growth, so perhaps school count isn’t catching something or a lot previous openings are still adding grades.

Virginia is a perennial laggard as well.

Data Feels Off

My guess is data is off in New Jersey, where multiple schools often open under one charter

New School Index 

Screen Shot 2016-02-14 at 7.38.28 PM

Net New School Index 

Screen Shot 2016-02-14 at 7.37.07 PM


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