Houston's economy can take a punch – or two.

By several measures, the oil bust that began three years ago and ended late last year was the worst downturn of its kind in history. Yet Houston's economy only suffered a mild recession; the region face nothing like the kind of ruinous depression that followed the collapse of oil prices in the mid-1980s.

The historic flood waters of Hurricane Harvey cost Houston thousands of jobs, left an $87 billion hole in balance sheets, severely damaged 39,000 homes and totaled 300,000 vehicles. But it will also spur a small boost of economic activity that will replace those jobs and spur a $2.6 billion surge in retail sales as people buy vehicles, furniture, and construction supplies to rebuild damaged homes.

Now the question is when Houston will return to the economic growth rate that defined the city and drew thousands to the region in the years after the Great Recession in 2009.

In his semiannual forecast on Monday, economist Bill Gilmer said the city's economic fortunes hinge most of all on whether the oil industry regains its footing after a slowdown in drilling this year.

If the drilling recovery in Texas oil fields like the Permian Basin and the Eagle Ford Shale continues to slow, but does not reverse, Gilmer forecast that Houston could add 69,900 jobs in 2018.. That 2 percent growth is around Houston's average job growth rate stretching back 25 years, Gilmer said.

That's about just as good as the average year when the region's economy was booming before the oil bust.

But in another scenario, in which drilling activity declines until early 2018, Houston would add 42,000 jobs; in a third scenario in which the oil industry regains its footing only late in 2018, the city will gain some 20,500 jobs.

"We're waiting for those oil jobs to return," said Gilmer, director of the Institute for Regional Forecasting at the University of Houston. "We've turned the corner. Looks like we have growth in front of us. We really need help from oil markets to heat up that growth."