From Arlington, I-20 passes into Dallas County at Grand Prairie and heads east in to Dallas, interchanging with I-35E south of downtown and I-45 shortly after. I-20 intersects with I-635 (where it completes a three-quarter loop around the city) on Dallas' southeast side before heading east toward East Texas. The Interstate varies from 4 to 10 lanes from its I-30 junction near Aledo to its US 80 junction near Terrell.
I-20 begins in Arlington, enters Dallas County at Grand Prairie, and travels east through Dallas, switching routes to I-35E south of downtown and I-45 shortly after. It intersects with I-635 (which completes a three-quarter loop around the city) on Dallas' southeast side before heading east toward East Texas. The Interstate has between 4 and 10 lanes from its junction near Aledo to its intersection with US 80 near Terrell.