“Energy prices are not the only factor that put these state budgets into disarray,” Carl Davis, the research director of the Institute on Taxation and Economic Policy (ITEP), told me. “There are conscious policy decisions being made here as well.” What’s happening across the country is that state legislatures have made decisions about taxation that don’t jive with the 21st-century economy. They’ve tried the supply-side model pushed by Reagan economist Arthur Laffer, who said cutting taxes could help spur job growth and spending to such a degree that revenue would not be significantly affected. They’ve found that this theory has not played out, and that although the recession is over, they’re still cash-flow negative.

For example, in an era of rising income inequality as the rich get richer, many states retain flat tax rates and can’t reap more money from those at the top of the economic ladder. Illinois, for instance, is one of eight states with a flat income-tax rate. (The state’s income-tax rate was 5 percent, but was lowered to 3.75 in 2015. That means someone making $500,000 a year in Illinois would pay just 3.75 percent in taxes, and someone making $50,000 would pay 3.75 percent as well. Minnesota, by contrast, taxes its lowest income bracket 5.35 percent, and taxes people making more than $258,261 at a rate of 9.85 percent.

Other states have cut taxes on the wealthy, creating their own budget deficits. Oklahoma slashed its top tax rate from 6.65 percent in 2003 to 5.5 percent in 2009 to 5 percent currently. Davis says this series of cuts reduced the state’s revenues by $1 billion. Kansas instituted massive income-tax cuts in 2013 that favored the wealthy, and the state has flailed since. North Dakota, buoyed by a booming economy and a seemingly endless (at the time) supply of oil and gas, cut both personal income taxes and corporate income taxes.

But it’s not just income taxes either. Motivated perhaps by Tea Party vigor, states have rolled back other forms of taxation as well. West Virginia has phased out both the grocery tax on food and its business-franchise tax, and has lowered the corporate-net income-tax rate, Davis said. Louisiana has offered big tax breaks to businesses who relocate there, as it rolled back tax rates for high earners.

What’s more, Davis says, state tax codes have not kept up with the changing nature of the economy. Many states still depend heavily on sales taxes, but people are buying fewer goods in brick-and-mortar stores. They’re buying fewer things in general, and instead spending more on services such as gym memberships, lawn services, and haircuts. Yet services are generally not taxed.

States that have tried to add taxes on services have not had much success. When Governor Martin O’Malley tried to expand sales tax to health-club memberships and tanning salons, he was met with fierce opposition. When D.C. put a tax on health clubs, the so-called “yoga tax,” confusion was widespread (in part because no one was sure whether yoga studios really counted as fitness centers).