(CNN) Arrests on the US-Mexico border dropped in January, marking a decline for the eighth consecutive month, according to data obtained by CNN.

There were around 29,200 apprehensions on the southwest border in January, a drop from the 32,858 arrests in December, data from US Customs and Border Protection showed. Apprehensions are used as a measure of illegal border crossings and an indicator of potential issues in other countries causing people to flee.

The numbers are down significantly from January 2019, when US Border Patrol arrested 47,979 people near the southern border. However, this month's arrests are higher than January 2018, when 25,975 people were apprehended.

The drop in apprehensions comes after a massive influx of migrant children and families arrived at US borders last year, overwhelming resources and straining agency morale. Migrants, including children, were held longer than the allowed 72 hours, and some border patrol facilities faced dangerous overcrowding.

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