In December 2015, the U.S. government reported that the number of migrant deaths along the border with Mexico fell for the third straight fiscal year, dropping from 308 in 2014 to 240 in 2015.
Officials attributed the decline to better surveillance of the desert and an improved ability to apprehend migrants stranded there. But some immigrant advocates questioned the meaning of the numbers, suggesting that they presented an incomplete and misleading picture.
Now data from Arizona suggest that the advocates may have been right.
Between 2004 and 2013, the number of deaths in Arizona reported each year by the U.S. Border Patrol was roughly on par with — or greater than — the number recorded by the medical examiner's office in Pima County, which collects the totals for all four counties along the state's southern border.
In 2014, however, the state and federal figures began to diverge, with the state reporting 127 deaths and federal officials 110. The spread was far greater last year, with the state reporting 143 deaths and federal officials 68.
That difference alone — 75 deaths — is more than enough to cancel out the borderwide improvement reported by federal officials between 2014 and 2015.
"If this were a plane crash, we would want to know the exact number of people who died," said Robin Reineke, executive director of the Tucson-based Colibrí Center for Human Rights, who was among the first people to notice the discrepancy in the numbers. "That's how we process the magnitude of an event. But we can't understand the impact of our border policy if we don't know how many people it is leading to their deaths."
The wide disparity in Arizona persisted in the first 11 months of this fiscal year, the most up-to-date figures available, with federal officials reporting 75 deaths, 53 fewer than the state reported.
Arizona accounts for 360 miles of the 2,000-mile-long U.S. frontier with Mexico. It is unclear whether the federal counts in other states are accurate, because no other entities are compiling the data. In other words, the federal government has no reliable count of the total deaths on the southern border.
Pima County officials aim to include all bodies that are found on the Arizona border, brought to the morgue and identified as migrants. In contrast, the Border Patrol only counts bodies of migrants its agents discover in the field.
The agency declined to answer questions about why its figures in Arizona have diverged so dramatically from the state numbers in the last two years.
"What we can tell you is that we can only represent that which we find," the agency said in a statement acknowledging that its figures were not the final word on migrant deaths.
That has not stopped the agency from lauding its own figures. "Border Patrol agents working along Arizona's border with Mexico stepped up their campaign in fiscal year 2015 to save distressed migrants while giving them options to call for help," the agency said in a press release in January. "As a result, agents report finding fewer deceased migrants."
Uncertainty over migrant deaths on the border is not new.
"Differences among [Border Patrol] coordinators in collecting and recording data on border-crossing deaths may have resulted in the data understating the number of deaths in some regions," the Government Accountability Office said in a 2006 report.
Even with the large gap between the state and federal numbers for Arizona this year, the Border Patrol is set to report an overall increase in migrant deaths this year along the entire southern border. In the first 11 months of fiscal year 2016, federal officials found the bodies of 287 migrants, 47 more than were found last year.
Times researcher Scott J. Wilson contributed to this report.
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