A “Mexican roadblock” (or “Mexican road block”) is when two cars travel at the same speed on both lanes of a two-lane highway (or three cars on a three-lane highway, etc.). This blocks cars from attempting to pass one of the vehicles. The drivers usually travel below the posted speed limits and are sometimes illegal aliens, without a valid driver’s license and/or automobile insurance.
 
The term “Mexican roadblock” dates from the 1990s and has been used in Colorado, Texas and a few other western states.
 
   
Urban Dictionary
Mexican roadblock
(n) May be created intentionally or unintentionally- two cars driving next to each other at the exact same speed, thus preventing you and other cars behind from passing. Unbelievably frustrating, especially when you have somewhere to be.
Always happens when I’m late to work.
I try to move to the right lane to prevent creating a Mexican roadblock.
by 83 Phoenix Jul 6, 2006
 
Urban Dictionary
Mexican road block
When driving on a road with two or more lanes going in one direction, and vehicles occupy all lanes. Said vehicles drive at the same speed and evenly, barring other vehicles from passing. This event native to Denver, where many “undocumented workers” usually from Mexico attempt to drive without a valid driver’s license or automotive insurance. These illegal immigrants therefore drive significantly under the speed limit, effectively infuriating all other drivers on the road.
Sorry I’m late for work today Mr. Jenkins. There was a Mexican road block on Interstate 25.
by Grego Brown Denver, Colorado Sep 10, 2006
 
Urban Dictionary
Mexican-Roadblock
A Mexican-roadblock occurs on a two or more lane road where 2 (or more) cars are traveling next to each other at the same speed (usually under the speed limit), not allowing the following traffic to pass. Most noticeable on the highway in a light traffic situation, where two cars stop the flow of traffic wishing to pass.
i was late to work because i got stuck behind stuck behind a mexican-roadblock
by carolus rex Jun 8, 2004
 
Racial Slur Database
Roadblock Mexicans
Called this because some have a tendency to travel slow, pacing one another on the freeway not allowing anyone else to pass. Mostly a Texas term, though it may be heard in any other of the ‘border’ states.
   
Google Groups: alt.autos.camaro.firebird
Newsgroups: alt.autos.camaro.firebird
From: .(JavaScript must be enabled to view this email address)
Date: 1997/05/14
Subject: Re: What kinds of cars are driven by assholes????
 
>>How about, when theres a car a ways in front of you, and they wait halfway
>>between that guy and you to finally decide to pull out, essentially cutting
>>you off when they could have come out right after the guy.
>I have nothing but sympathy for that. How bout, on a two lane highway.
>The person swings out to the left lane to pass the slower car in fron
>of him…but only goes one mile over the speed limit to pass,
>therefore you have 2 slow pokes blocking both lanes.
 
Ah yes, the ‘Mexican Road Block’...actually done that on purpose a couple of times.
 
Google Groups: rec.autos.4x4
Newsgroups: rec.autos.4x4, rec.autos.driving, rec.autos.makers.chrysler, rec.autos.makers.ford.explorer, rec.autos.makers.ford.mustang
From: “Rich Osborne”

Date: 1998/08/29
Subject: Re: speeding/left lane/courtesy (was Re: SUV’s…...getting out of hand)
 
And I still admit there is nothing more fun then sitting right at the speed limit in the left lane and watching for fed up these people get by.  I’m usally laughing or smiling as they finally give up and go around.  The really bad flashers of the group I make sure I take my time passing other cars creating the old mexican roadblock trick.