The importance of passenger transport companies to facilitating mass migration have generally been acknowledged. Their paradoxal role as obstructers of the same, being an integral part of our modern day border enforcement system, has received much less attention. This article analyses the use of transport companies by states to monitor and restrict migration. It focuses on the recent historiography of the role of shipping companies in regulating migratory movements during the long nineteenth century. It stresses the importance of acknowledging the influence that transport companies had on the enactment, enforcement, and evasion of human mobility controls in future research.