How to secure the southern border of the U.S. will command the spotlight in the coming weeks as President Trump and Congress again seek a compromise to prevent another government shutdown or a national security emergency declaration.

The president continues to demand expansion of physical barriers. Others are convinced technology provides more cost-effective means to defend the 1,933-mile southern border with Mexico, much of it through rough and lightly-inhabited terrain, where fencing may be less useful in stemming illegal crossings.

“Let’s make sure we’re using the right tools in the right place,” Rep. Will Hurd, R-Texas, told the New York Times. Hurd’s district includes a long stretch of the U.S./Mexico border. House Majority Whip Jim Clyburn, D-S.C., recently told NBC News that technology would be a superior option to the physical wall that the President demands.

In 2016, the Border Patrol tested crowdsourcing technology to monitor the border and provide humanitarian assistance with the use of a mobile app called GridMeNow. This technology allowed ranchers, border residents, and trusted users to connect directly with Border Patrol and provide them with exact GPS coordinates of any border observation, such as the discovery of migrants in physical distress. They were able to quickly send the geo-location of their observations as photographs or video.

The Border Patrol relied on the information it received from this application much more than many of the remote sensors that existed along the border. “It’s a tool for us to better communicate and generate precise locations” in remote areas where “911 calls are not precise,” Border Patrol Agent in Charge Tom Slowinski, who works the Rio Grande Valley in Texas, told KRGV-TV in Weslaco, Texas.

Homeland Security Department budget issues led to GridMeNow’s termination. But it won plenty of fans during its two-year demonstration, including the late Sen. John McCain and retired Gen. Stanley McChrystal.

In a single month of use, reports from GridMeNow users in Slowinski’s area–centered around Falfurrias, Texas–led to 15 arrests, three rescues, the identification of four suspect vehicles, and three smuggler identifications. The app also was used in the Douglas, Arizona sector, the Spokane, Washington sector, and Detroit.