A.T. Robertson Commentary Acts 16:8

"and passing by Mysia, they came down to Troas." — Acts 16:8 (ASV)

Passing by Mysia (παρελθοντες την Μυσιαν). Literally, passing alongside or skirting Mysia, neglecting it without preaching there. Strictly they passed through part of it to reach Troas.

To Troas (εις Τροιαδα). This city, named Alexandria Troas after Alexander the Great, was the seaport of Mysia, though a Roman colony and not counted as part of either Asia or Bithynia. New Ilium, on the site of the old Troy, was four miles farther north. It was the place to take ship for Philippi. Twice again Paul will be here (2 Corinthians 2:12; Acts 20:6).