PRINEVILLE, OREGON, IS home to only about 10,000 people but to hundreds of thousands of servers. In January 2010 Facebook decided to build a huge data centre on a 124-acre plot in the high, juniper-pocked desert east of the Cascade mountains. The first building is as long as an aircraft carrier. A second, nearing completion, is slightly bigger.

Facebook is not alone. Bulldozers are chugging away on a 160-acre site nearby, digging for Apple. The iCloud will be housed here, in far-from-nebulous concrete and metal. The state boasts a growing collection of such centres (see map). Google landed farther north, in The Dalles. Amazon is in Boardman, on the Columbia river, which marks the border with Washington state. Rackspace, a fast-growing keeper of other companies’ data, is planning a facility in the same town. A group of smaller centres is clustered around Portland.

The internet, as Andrew Blum vividly describes in his book, “Tubes”, published this year, is a physical entity. Mr Blum, a journalist with Wired, a technology magazine, traced his way through the internet, from the wire that goes out of the wall of his house, along the street and thence through fibre-optic cables, into exchanges where network operators’ cables meet, through routers and switches, to data centres (including Facebook’s and Google’s in Oregon) and back home again.

All this equipment has to be kept somewhere. And as Mr Blum shows for several different types of kit, once one big company installs a load of equipment, for whatever reason, others are likely to be drawn to the same place.

The amount of data being generated is growing at an eye-popping pace: IBM estimates that 2.5 quintillion bytes are being created every day and that 90% of the world’s stock of data is less than two years old. A growing share of these data is being kept not on desktops but in data centres—buildings containing rack after rack of computers.

Even in the age of superfast fibre-optic cables, companies do not like their data to travel too far. “Concern about latency [delay] used to be the privilege of big corporates, but it has started to matter again for a certain number of applications,” says Vivek Badrinath, chief executive of Orange Business Services, the enterprise arm of France Telecom-Orange. Companies with salesmen on the road, for instance, want orders to be entered and processed at once. His data centres are at most 150 milliseconds away from any big city. Distance is not dead; but it is measured in time not space.

Some data, such as financial and medical information, are more sensitive than others. There are regulations and strict certification of the conditions in which they can be kept. At BendBroadband, about 30 miles from Prineville, the main customers of a new centre that opened last year are health-care and financial institutions.

Awesome Oregon

Many companies rent space in shared (or “co-location”) centres belonging to companies such as Rackspace or BendBroadband. Some, such as Amazon or Google, are big enough to build their own. Facebook too has outgrown co-location. It had been renting space in California and Virginia, but needed sites of its own. It wanted one in the western states, to serve users on that side of the country and with good connections to Asia. It is also building centres in the east, in Forest City, North Carolina (a state that also plays host to Apple, Google and others), and in Europe, at Lulea, in northern Sweden. But why did it choose a little town in the Oregonian desert, miles from anywhere?

Jay Park, who runs the company’s design, construction and operations teams for data centres, says Prineville is the “ideal location for the evaporative cooling system” that Facebook uses. Data centres are power-hungry beasts. Energy accounts for much of their operating cost, both to supply the servers and to cool them. Most contain a water-chiller which cools the air in the server rooms, consuming lots of energy.

Facebook, though, cools its centres with the dry (and often chilly) desert air, which enters a chamber on the roof of the building and is mixed with warm air recycled from the server room—a little in summer, a lot in winter. After passing through two sets of filters, the air is misted with high-pressure water sprays, then pulled through an array of fans. From there it drops into an aisle in the server hall where a perforated metal plate slows it down and helps distribute it around the server racks. Warm air is returned to the mixing chamber where the process began and used to heat offices if the weather is cold or expelled from the building if it is hot. The centre’s design also contains other elements intended to keep energy costs down. All in all, Facebook gets a lot of cooling in Prineville for nothing.

But the weather was not the only reason for coming. The town is close to the main carriers’ fibre routes, and connections to Asia, via Portland, are good too. When Facebook first arrived, the site was only about half a mile from high-voltage electricity lines running from Washington to California, although the company has since had to add a longer spur, adding to its costs. Labour was available both to build the centre and to run it.

Another big reason, perhaps as important as the climate, was tax. Oregon is one of only five states with no sales tax. “You replace a server every three years and a server costs a lot, so sales tax is a big deal,” says Mr Park. Electricity can be cheaper elsewhere, but Mr Park reckons that “the power rate is easier to change than the tax law.” In Washington state, which also has a cluster of data centres (Microsoft, among others, is at Quincy), legislators have been willing to make deals with inward investors, but in Oregon there is no need for special arrangements.

The other main incentive is a concession on property taxes. In rural enterprise zones, which include Boardman and The Dalles as well as Prineville, investments are exempt from these for up to 15 years provided that they create at least 35 jobs and wages are at least 50% above the local average.

In damper western Oregon, John Sheputis, chief executive of Fortune Data Centers, a co-location operator based in San Jose, has just opened a data centre at Hillsboro, near Portland. Hillsboro may not have a desert climate, but it has bags of infrastructure. Fortune’s site is a stone’s throw from a huge Intel semiconductor factory, which brought with it a plentiful, reliable (and pretty green) power supply. It also attracted contractors that specialise in building “mission-critical” facilities such as data centres, which need to operate around the clock without fail. The risk of lightning, the biggest cause of power cuts, is low. Hillsboro sits on top of the main domestic and transpacific fibre networks. And it is near Portland’s busy airport, making it easy for Mr Sheputis’s tenants to visit.

Again, the absence of sales tax counts for a lot; and in urban western Oregon, Mr Sheputis needed to create only one new job to be exempt from property tax. Without its tax system, he says, the state “wouldn’t be as compelling”. With it? Given the same rents, even if power were free in California, he reckons he would still be better off in Oregon. “If you’re west of the Mississippi and you’re not in Oregon, you’re paying too much,” he says.