The railway involves a natural monopoly: the only other way of getting to the ruins is a four-day hike along the Inca Trail.

ECONOMIST: The battle to reach Machu Picchu

Yesterday the state natural gas monopoly, Gazprom, signed a deal to take control over the country's largest foreign investment, the massive Sakhalin II Gas Complex in the Russian Far East.

NPR: Russia's Putin Makes Trip to Neighboring Ukraine

The network effect of eBay might seem like a natural monopoly in the making.

ECONOMIST: eBay

On the Internet backbone, where there is no risk of a natural monopoly, collaboration is already the pattern.

ECONOMIST: The future: Tomorrow’s Internet | The

Leaving only the intractable core of that natural monopoly to be either public or private and regulated.

FORBES: Which Should We Have: Public Utilities Or Regulated Private Monopolies?

Because cable is a natural monopoly: digging up the streets is so expensive that cable companies seldom compete with each other.

ECONOMIST: Beware the gatekeeper | The

The 1992 Cable Act incorrectly assumed that cable was a natural monopoly requiring permanent, extensive, and intrusive regulation of cable rates and content prices, terms and conditions.

FORBES: Obsolete Television Law Needs Modernization