The US was involved in a long-running NAFTA dispute with Mexico over trucking:
Although the charter of the North American Free Trade Agreement established a schedule that would have opened the border states of the United States to competition from Mexican trucking companies in 1995, and all of the United States to this competition in 2000, the full implementation of these provisions has been delayed due to concerns about the safety of Mexican trucks and drivers. This delay has resulted in much frustration for Mexico, which, in 2009 implemented retaliatory tariffs on products imported from the United States. In March, 2011 the two countries unveiled a deal to resolve this dispute which could help ease tense relations between the two neighbors.
More recently, US truckers have challenged the DOT decision in courts
The Teamsters, along with truck safety groups, sued DOT in March 2015, arguing that a report issued by regulators that deemed Mexican trucks safe enough to operate domestically didn’t pass legal muster because of the program’s low participation rate. A federal appeals court will hear oral arguments on the case on March 15 [of 2017].
Have there been any developments since then? Are Mexican trucks currently still allowed to operate in the US, beyond buffer zone around the border? If so, how much trucking do Mexicans do in the US?