left lane lag

a condition on limited-access high-capacity arterial roadways aka freeways where a disproportionately large convoy of vehicles occupies the "number one" aka left-most lane in anticipation of passing sauntering traffic in the other lanes. The cause of the build-up is often a beltway bitch or a motorist who is passing other slower motorists at a marginally higher velocity, often less than 1 mph greater, often out of fear that s/he may be pulled over for speeding if s/he goes any faster. Warning: this condition often creates freeway fags.