the ports-to-plains corridor starts at the mexico–united states border at a bridge crossing in laredo, texas, where it meets and runs concurrent with i-35, a six-lane freeway. north of laredo, the route follows us 83, a two-lane highway to carrizo springs, texas, where the route follows us 277 through eagle pass, del rio, sonora, and san angelo, texas. north of san angelo, the route follows us 87, a four-lane highway, through big spring and lamesa and finally to lubbock (an alternate route passes through midland and odessa instead of big spring.)