AMERICA appears to be a much less inviting prospect to migrants than it once was. This may please some lawmakers, who might point to the effectiveness of tough state-level laws and at improved border security. But although $12 billion will be set aside to guard the frontier in the next fiscal year, fewer people are actually being caught trying to cross it. In 2007, 20% fewer arrests were made by the Border Patrol than in 2006. In the six months to March this year, arrests are down by 17% on a year-to-year basis. Using this imperfect measure, migration has slowed dramatically. Big fences and hostility do play a part, but the economy is a big factor. In boom times, more arrests are made at the border as more people cross looking for work.

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