From Reason:

Unlike the federal government, states can’t simply run deficits indefinitely. For that reason, they have a powerful duty to pile up surpluses during fat years, which would allow them to make up the revenue that goes missing during lean years. But for many lawmakers, the future extends only to the next election. So any money they have, they feel an insatiable need to lavish on someone.
Politicians are happy to blame the recession for depriving citizens of programs they have come to expect. The recession didn’t create the gap between state government commitments and state government resources. It only exposed it.

For instance:

In state after state, the government’s take has ballooned. Overall, the average person’s state tax burden has risen by 42 percent since 1999—nearly 50 percent beyond what the state would have needed just to keep spending constant, with allowances for inflation.
Even low-tax states like Texas and Nevada have followed the same course. No one has been inclined to say, “Taxpayers don’t need to send us more money. We’ve got plenty.”
All that growth should have been enough to pay for essential programs and furnish ample reserves, allowing state governments to weather a downturn without major adjustments. But the states put a priority on burning through all the cash they could get. Last year, they spent about 77 percent more than they did 10 years before.

We know that’s true around here. Heck, we even managed to have a budget 12% higher this year! Party-on.