Macedonia declared a state of emergency this week. The problem? A 30-mile-long stretch of its border with Greece where Macedonian police and soldiers are struggling to control what they describe as a "massive" influx of migrants. Things turned violent on Friday: Macedonian special police forces fired stun grenades to disperse a crowd of thousands. Greek police say at least eight people were injured in the chaos, with one child apparently cut open by shrapnel from a grenade, the Associated Press reports.

Macedonia is just the latest hot spot in a continent-wide migrant crisis that, in some ways, is starting to resemble a war. In Britain, the tabloid press demands that the army be sent to France to prevent migrants entering the Channel Tunnel. In Hungary, there are plans to build a giant wall along the border with Serbia. And in the Mediterranean, Frontex, the European border agency, has boats working security rather than search-and-rescue missions, despite the death by drowning of thousands of migrants making the journey from North Africa.

The country's situation also shows how complicated and multi-faceted the crisis has become, however. Few of those massing at the Greek border are hoping to stay in Macedonia, a former part of Yugoslavia with a relatively low GDP per capita. Instead, it has become a stop on what Frontex refers to as the Western Balkans Route but others refer to more ominously as the "Black Route."

Migrants who use this route tend to first arrive in Greece via boat from Turkey. While Greece is a member of the European Union, its economic troubles mean it is not a desirable place for migrants to stay long-term. Instead, they head north, crossing the border with non-E.U. member Macedonia that has been relatively porous until recently, with an estimated 2,000 people a day making it across.

Once in Macedonia, they take trains or work with people-smugglers to reach Serbia, from which they stand a chance of entering Hungary, an E.U. member. If they can get into Hungary, they have made it to the Schengen area, a grouping of 26 European nations that have abolished border controls among them, meaning transit becomes easier. According to the nstitute of Migration, more than 80 percent of those who arrive in Hungary head for Western Europe after a few days.

The sheer numbers of people coming to Macedonia may stem in part from the country's own policies. In June, realizing that the scale of the migration occurring on its soil was making it difficult to police, the Macedonian government passed a law allowing asylum seekers 72 hours to pass through the country using legal means such as public transportation. The Christian Science Monitor's Kristen Chick reported that this resulted in migrants congregating in Gevgelija, a town on the Southern border with Greece, to register. The Black Route appears to have become an increasingly attractive option for getting to Europe recently: Some 39,000 migrants registered as migrants passing through Macedonia over the past month, according to the AP, double the number who had registered the month before.

Most of those reaching Macedonia hope to seek refuge in Europe from conflicts in places such as Syria, Iraq and Afghanistan. Earlier this year, The Post's Anthony Faiola followed one Syrian family as they made their way through along the Black Route. “We would only die once in Syria,” Ahmed Jinaid had said not long after the family left Macedonia. “Here we are dying 5,000 times.”

In a statement released on Friday, the United Nations' refugee agency expressed concern about the closure of the Macedonian border, which it said left "thousands of vulnerable refugees and migrants, especially women and children, now massed on the Greek side of the border amid deteriorating conditions."

Macedonian riot police fire tear gas to disperse thousands of migrants and refugees attempting to enter the country from Greece. (Reuters)

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