Pro-immigration activist Ricardo Reyes yells at anti-immigration activists during a protest along Mt. Lemmon Road on Jully 15, 2014 in Oracle, Arizona.National Journal

The border crisis is constantly in the news these days, and it's gotten Americans concerned: One in six now say immigration is the most important problem facing the U.S. today. In June, only one in 20 Americans had the same answer.

A Gallup Poll released today shows that immigration is neck and neck with dissatisfaction with government for the title of most-important U.S. problem. Of the Americans polled, a combined 33 percent said that one of those two issues is the most pressing. The economy and unemployment follow as contenders for the focus of Americans' worry.

But a look at the historical data shows that immigration rarely ranks as high as it did in July. In January, only 3 percent called it the most pressing issue. By contrast, some facet of the economy has been the top concern for at least 40 percent of Americans since 2008, peaking at 86 percent in 2009.

The intermittent attention that immigration receives is driven in large part by events that thrust the issue into the spotlight. Concern over immigration last peaked once in 2010 and twice in 2006: The 2010 peak corresponded with news of a controversial immigration law in Arizona; 2006 saw congressional debate over immigration reform.

A partisan split in today's data is telling: Twice as many Republicans as Democrats pointed to immigration as the most pressing issue, suggesting that concern over illegal immigration, rather than immigration reform toward a pathway to citizenship, is driving public interest.

Given how quickly immigration surged into the spotlight and how fast concerns over health care have faded — it was the top concern for 16 percent of Americans in January and now clocks in at 8 percent — it's likely that this wave of interest will quickly be swept aside by the next big issue in Americans' minds.

The Gallup Poll surveyed 1,013 adults in all 50 states and the District of Columbia from July 7-10. The margin of error is plus or minus 4 percentage points.

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