Chart 6 > Border Mexico-USA
Mexico–United States border/Length 3,145 km /1,954 miles
Some 700 of those miles have fencing in place.
Photographer John Moore has driven “every inch” of the border while covering the immigration issue for over a decade. He’s spent time on both sides, tagging along with Border Patrol agents and migrants.
Through his photos, you can see how the fencing varies greatly on different parts of the border.
The 650 miles of fencing built under President George W Bush cost an estimated $7bn
Just before 2016, there were 654 miles (just over 1,000km) of barrier along the southern border - made up of 354 miles of barriers to stop pedestrians and 300 miles of anti-vehicle fencing.
Since January 2016, although some of the already existing barriers have been replaced, work on extending the current barrier has only just begun.
Just over 40 miles of replacement barriers had been built or begun by the end of 2018. Construction was expected to start on 61 more miles of replacement barrier in 2019. This equates to new sections of about 15% of existing structures.
The first construction on any extension to existing structures - what could be termed new barrier - was planned to start in February in the Rio Grande Valley, Texas.
Some 33 miles (53km) of barrier - or what US Customs and Border Protection calls "border wall system" - is to be erected in Hidalgo and Starr counties in the Rio Grande Valley (25 miles and eight miles respectively).
However, construction at five major landmarks along its length has been prohibited and some landowners have gone to court in an attempt to stop building on their property.
Most of the border seizures were in the San Diego corridor - approximately 1,073kg in 2017, a 59% increase on the previous year.
While most of the heroin in the US does come from Mexico, the DEA says the majority of it is smuggled in through legal ports of entry, hidden in privately-owned vehicles or transporter lorries, mixed with other goods.
Only a small percentage of the heroin seizures were between entry points - where barriers exist or are proposed.
In fact, there are already barriers in border patrol sectors with the highest volumes of heroin seizures.
The Border Patrol gained a total of 120 agents in 2018, the first net gain in five years.
In March 2017, McAleenan said Customs and Border Protection normally loses about 1,380 agents a year as agents retire, quit for better-paying jobs or move. Just filling that hole each year has strained resources.