Maybe Prineville will be visible from outer space.

Facebook said Thursday it will spend $750 million to build two more massive data centers on the outskirts of the tiny central Oregon town. The project will expand the company's complex to seven buildings and bring its total investment in the neighborhood of $2 billion.

At 3.2 million square feet, Facebook's Prineville footprint will be equivalent to putting 22 Costco stores in a community of just 10,000 people.

The gigantic scale notwithstanding, data centers are not major employers: They are cavernous, dark and mostly devoid of people, consisting of dozens or hundreds of rows of computer servers packed tightly together.

Facebook said it will add as many as 100 jobs to Prineville to accommodate the expansion, lifting its total workforce past 350. But the tally includes a large number of security contractors.

Facebook, like other Silicon Valley companies, houses its data centers in Oregon because of the state's uniquely generous tax breaks. Property tax exemptions save the social networking company nearly $20 million a year, and those savings will grow as Facebook continues building.

Crook County probably isn't giving up anything, though, since Facebook is on previously vacant desert land it bought from the county -- property that wasn't even on the tax rolls before the company opened its first corporate data center in 2012. Apple has a smaller server farm complex just up the road.

Energy used from the data centers produces $2 million in franchise fees annually, which go straight to Prineville's general fund. The city says they account for 4 percent of the city's total budget.

Thursday's announcement comes just nine months after Facebook announced its last Prineville expansion, growing from three to five data centers. The company didn't explain why another expansion is in the works so quickly, but the entire data center industry is growing rapidly as people post video and photos to their social networks and as companies move more of their computing to off-site data centers.

Intel -- Oregon's largest corporate employer -- is a major beneficiary of that growth, since it makes nearly all the processors inside the high-end computers stacked inside these data centers. The company's data center segment recorded $5.5 billion in sales last quarter, up 27 percent from a year earlier.

Facebook said in July it would finance six large solar projects, including two near Prineville, that will provide clean power to offset its energy use at the Oregon facilities. The company indicated it plans more clean energy projects to offset the additional power use from the two new buildings.

Thursday's expansion will take nearly two years to build, according to Facebook, and employ 1,500 construction workers at its peak.

The influx of data center construction workers has strained Prineville's housing supply, which is tight in the city and in neighboring communities amid a roaring comeback in the regional economy.

Prineville City Manager Steve Forrester said officials are working with multiple developers on temporary workforce housing and expect to open a 29-unit, low cost housing unit. And, he said applications for new development are up sharply, already matching the total 2017's total.

-- Mike Rogoway | twitter: @rogoway | 503-294-7699