Per-student funding for existing programs during that year dropped to an average of $3,841 for each student. It was the first time average spending per student dropped below $4,000 in today's dollars since researchers started tracking it during the 2001-02 academic year.
Adjusted for inflation, per-student funding has been cut by more than $1,000 during the last decade.
Yet nationwide, the amounts were widely varied. The District of Columbia spent almost $14,000 on every child in its program while the states of Colorado, South Carolina and Nebraska spent less than $2,000 per child.
"Whether you get a quality preschool program does depend on what ZIP code you are in," Barnett said.
Among the 40 states that offer state-funded pre-K programs, 27 cut per-student spending last year. In total, that meant $548 million in cuts.
Money, of course, is not a guarantee for students' success. But students from poor schools generally lag students from better-funded counterparts and those students from impoverished families arrive in kindergarten less prepared than others.
In all, only 15 states and the District of Columbia spent enough money to provide quality programs, the researchers concluded. Those programs serve about 20 percent of the 1.3 million enrolled in state-funded prekindergarten programs.
"In far too many states, funding levels have fallen so low as to bring into question the effectiveness of their programs by any reasonable standard," researchers wrote.
Part of the reason for the decreased spending are the lingering effects of the economic downturn in 2008, coupled with the end of federal stimulus dollars to plug state budgets.
"Although the recession is technically over, the recovery in state revenues has lagged the recovery of the general economy and has been slower and weaker than following prior recessions. This does not bode well for digging back out of the hole created by years of cuts," the researchers wrote in their report.
Nationally, 42 percent of students -- or more than a half million students -- were in programs that met fewer than half of the benchmarks researchers identified as important to gauging a program's effectiveness, such as classrooms with fewer than 20 students and teachers with bachelor's degrees.
That, too, suggests problems for Obama's plan to expand pre-K programs, especially if Washington insists its partners meet quality benchmarks to win federal dollars.