When each month's local jobs numbers come along, no matter how ugly they are, it's tempting to say: Those aren't nearly as bad as the 1980s. Heck, they're not even as bad as the recession six years ago.

By many metrics, that's true. Outside the oil sector, layoffs haven't been as deep and the economy doesn't feel as unstable in Houston in downturns past. The difference with this one, and the danger, is its duration: Using a diverse set of indicators that measure economic activity, businesses have been contracting for nearly twice as long as they did after the financial crisis.

That's what we can learn from the June Purchasing Manager's Index, which is tabulated by asking businesses whether they're doing better this month than last month, when looking at factors like new orders, expenses, payrolls, and inventories. This month marked eighteen months in a row where more respondents said business is getting worse rather than better.

Certainly, things haven't gotten as bad as they did during the worst of the last recession in 2008 and 2009, when the index plunged to 39 on a scale of zero to 100, with readings below 50 indicating contraction. That's the lowest level since the Houston chapter of the Institute for Supply Management started taking measurements in 1995. The lowest reading during this downturn was 42.7, in April 2015.

But the recessionary downturn lasted less than a year, as the oil and gas turbocharged the Houston economy back into positive territory. Although the rate of job losses in the oil and gas sector has slowed as of late, it's not clear when that might happen again -- if ever. And businesses can only contract for so long before dying of exhaustion.