A year ago, it seemed, for a moment, that Mr. Maduro’s critics might have a chance to oust him. An opposition leader, Juan Guaidó, had staged the biggest challenge to Mr. Maduro’s rule to date by claiming the presidency and quickly winning support from the United States and almost 60 other countries.

Now Mr. Maduro’s adversaries have lost momentum. The Trump administration remains supportive of Mr. Guaidó: On Monday, the United States issued new sanctions against government allies who tried to block him from assuming the leadership of the country’s National Assembly. Despite this pressure, Mr. Maduro’s tenure seems secure, in part because of how well Mr. Maduro’s policies have bolstered Caracas.

[Update: The U.S. has imposed sanctions on the Russian oil company supporting Venezuela’s leader.]

But the economy, suffering from poor management, diminished oil and gold exports and crippling sanctions by the United States, is now entering its seventh year of a devastating contraction.

This lasting depression, along with the retrenchment of the state, has allowed much of the nation’s infrastructure to fall into neglect.

It has also led to Venezuela’s breakup into localized economies with only nominal links to Caracas. As runaway inflation rendered the country’s currency, the bolívar, practically worthless, dollars, euros, gold and the currencies of three neighboring countries began to circulate in different parts of Venezuela. Barter is rampant.