US Customs and Border Protection (CBP) have wide-ranging powers to search phones and other devices of anyone entering the US, including citizens.
Figures for the three months up to June this year show a significant increase in device searches, with almost 15,000 devices searched – the highest number for any three-month period.
This comes as the Trump administration looks to crack down on migrants entering the US.
The CBP says the number of travellers who experience a border search of their electronic devices is small, with less than 0.01% of international travellers affected.
However, the ACLU has warned the searches are having a chilling effect on travellers, especially those who are critical of the Trump administration, or who are lawyers or journalists and may have sensitive information on their devices.
