(a) Definitions
In this section—

"safety rest area" means a roadside facility with parking facilities for the rest or other needs of motorists.

"truck stop" means a facility (including any parking lot appurtenant thereto) that—

(A) has the capacity to provide fuel or service, or both, to any commercial motor vehicle (as defined in section 31301 of title 49), operating in commerce (as defined in that section); and

(B) is located within 2,500 feet of the National System of Interstate and Defense Highways or the Federal-Aid Primary System.

(b) First offense
A person who violates section 841(a)(1) of this title or section 856 of this title by distributing or possessing with intent to distribute a controlled substance in or on, or within 1,000 feet of, a truck stop or safety rest area is (except as provided in subsection (b)) ¹ subject to—

(1) twice the maximum punishment authorized by section 841(b) of this title; and

(2) twice any term of supervised release authorized by section 841(b) of this title for a first offense.

(c) Subsequent offense
A person who violates section 841(a)(1) of this title or section 856 of this title by distributing or possessing with intent to distribute a controlled substance in or on, or within 1,000 feet of, a truck stop or a safety rest area after a prior conviction or convictions under subsection (a) ² have become final is subject to—

(1) 3 times the maximum punishment authorized by section 841(b) of this title; and

(2) 3 times any term of supervised release authorized by section 841(b) of this title for a first offense.