DUBLIN — Most migrants who live illegally in the European Union fly to the 28-nation bloc on valid visas and simply overstay their welcome. But for the poorest and most desperate travelers of Africa, Asia and the Middle East, the journey often takes months by sea or land, with payments to trafficking gangs.
Frontex, the EU agency that helps member nations detect migrants on the bloc's frontiers, documents the flow of illegal immigration on principal smuggling routes. These keep evolving in response to every government initiative.
Ewa Moncure, spokeswoman for the Warsaw-based agency, compares efforts to quell immigration on any particular route to "squeezing a balloon."
"You tighten a law in one country, another route swells up elsewhere," she says.
Here are the main four smuggling routes listed in order of popularity in 2014 as recorded by Frontex. Each lists the total number of migrants detected in destination EU countries last year, the change from 2013, and the top three nationalities of migrants.
CENTRAL MEDITERRANEAN: By boat to Italy.
Most sail from the anarchic coast of Libya to Italy's southernmost islands or fellow EU member Malta. More than 170,000 reached Italian soil on this route in 2014, quadruple the previous year and a record annual figure for any country in EU history.
Numbers have surged since the 2011 overthrow of dictator Moammar Gadhafi, who had enforced a bilateral agreement with Italy. The overcrowded boats sometimes capsize; an estimated 3,500 drowned last year. Syrians, Eritreans and sub-Saharan Africans are the most common travelers.
EASTERN MEDITERRANEAN: By boat or land from Turkey to EU members Greece, Bulgaria or Cyprus.
Numbers are soaring because of Turkey's hosting of more than 1 million refugees from Syria, Iraq and Afghanistan; its policy of making air travel from Africa easy; and, above all, its intimate proximity to the eastern islands of Greece.
While land border controls have been toughened, it's proved harder to stop migrants from completing trips to Greek islands just minutes from the Turkish coast using smuggler-supplied rigid inflatable boats. More than 50,000 used this route last year, double the 2013 figure, led by Syrians, Afghans and Somalis.
WESTERN BALKANS: From Greece to Hungary via Macedonia and Serbia.
This is the fastest-growing smuggling route, and increasingly the seamless second half of the Eastern Mediterranean route from Turkey.
Once reaching Greece, asylum-seekers cannot easily reach other EU states except through the former Yugoslav nations of Macedonia and Serbia. Neighboring Hungary has become the preferred EU opening for travel by road or rail to immigrant favorites Germany and France. Many walk the entire Macedonian section because locals refuse to drive the migrants, citing harsh anti-smuggling laws.
Alongside the Greek influx, the Balkans themselves generate heavy illegal immigration to the EU, particularly from Kosovo.
More than 43,000 were recorded arriving in Hungary in 2014 using this route, double the previous year. Kosovars, Afghans and Syrians led the way.
WESTERN MEDITERRANEAN: By boat from Morocco or Algeria to Spain, or by land to Spanish outposts in North Africa.
Once a top route for people-smugglers, but Spain's tightened border security and bad economy have limited growth of migrant numbers.
Relatively few attempt to breach security barriers to Melilla and Ceuta, Spain's enclaves on the Moroccan coast. Instead, migrants use private boats and public ferries from Algeria and Morocco to reach Spain's Balearic Islands and mainland. Just to reach the North African coast, many Africans must walk for weeks along the Atlantic coast or through the Sahara Desert.
Spanish border guards recorded 7,840 used this route last year, barely 1,000 more than in 2013, led by migrants from Cameroon, Algeria and Mali.
"Eastern Borders" is Frontex's umbrella term for dozens of potential routes along the EU's 6,000-kilometer (3,600-mile) frontier with Russia, Ukraine, Belarus and Moldova. The EU side — chiefly Finland, the three Baltic states and Poland — employ firm border checks that keep illegal immigration relatively static, including 1,270 migrants recorded in 2014, half coming from Vietnam, Afghanistan and Georgia.
The Western Africa route, involving boatloads of Africans arriving in Spain's Canary Islands, was Europe's busiest route a decade ago. Tougher enforcement means migration has slowed to a trickle, with only 275 arrivals in 2014 — less than 1 percent of the levels recorded in 2008.