An article in todays NYT magazine, brought to my attention by someone who is one of the anonymous donors to the program.
Philanthropists will cover the in-state tuition costs of any student who graduates from the district high school, prorated on when they start - kindergarten - 12 will get you 100%, beginning as a high school freshman with get 60-something percent.
Its a lengthy article, to long to copy and paste, but brings up some interesting ideas about investing in public schools, and how this program reversed the decline in student numbers, brought in more investment, and helped reinvigorate the town.
That doesn't happen in a vacuum, of course, and the results aren't spectacular, but better than they were. Article lists some of the other influences and town attributes, all contributing.
Denver schools tried this as well, and there were only a few who managed to graduate and take advantage of the program. One reason it didn't work so well here was that many of the eligible kids turned out to be here illegally.
Here is a link that might be useful: link