After a hard winter, Cullen and Elam travel to New York to secure their positions on the railroad as Durant fights for his legacy from prison.

An unexpected roadblock forces Cullen to make a difficult choice as a reporter arrives in Hell on Wheels. Elam struggles with his new boss.

Cullen and Elam search for their stolen food on the prairie; a stranger's arrival threatens Elam's family.

Cullen and Elam try to secure a new lumber source following a railroad accident; Durant tells Louise a secret about Cullen.

Cullen helps Elam track down a dangerous criminal; the town prepares to move down the tracks.

Durant files an injunction against Union Pacific, threatening Cullen's position; Elam deals with a dangerous newcomer.

When a cholera epidemic hits Hell on Wheels, Cullen must find fresh water before his workers die. Durant faces political fallout.

After his workers defect to the Mormons, Cullen recruits Durant to help get them back. Meanwhile, Sean and Mickey's past comes back to haunt them.

With General Grant's deadline only two days away, a gang of riders attacks Cheyenne while Cullen and Elam pay Durant a visit.

Cullen grapples with consequences while Elam mounts a rescue attempt. Durant receives Gen. Grant and the U.P. board in Cheyenne ahead of the deadline.

Cullen awaits the birth of his baby, laboring under The Swede's thumb at Fort Smith. Durant deals with the fallout from a railroad accident.

As Cullen plans an exit from Fort Smith, he challenges The Swede; when a new adversary arrives, Cheyenne feels his presence.

Cullen goes back to work on the railroad and butts heads with his new boss. Durant and Campbell battle over a valuable piece of real estate.

Cullen deals with trouble at home as he takes railroad matters into his own hands. Campbell makes a move against Durant and Mickey.

Cullens's family is at risk when a stranger arrives, stirring up old feelings; The Swede faces the consequences.

Following an attack by a bear, Elam struggles to survive in a Comanche village and find his way back to Cheyenne.

Cullen attempts to reconnect with Elam upon his return. Durant takes matters into his own hands while putting an old problem to rest.

Cullen makes a decision to ensure his family's safety. Campbell hires a new federal marshal to clean up the streets.

Cullen goes head to head with the new marshal to recover his arrested railroad workers. Campbell confronts Louise over a story.

Cullen, Durant, and Campbell try to negotiate a settlement on how the streets will be policed. An act of terror strikes Cheyenne.

Cullen and Durant fight to save the life of a criminal. Meanwhile, Louise tries to provide support as Ruth copes with a great loss.

Cullen grapples with Ruth's unexpected decision; Louise jeopardizes her reputation to fight for a story she believes in.

As the railroad prepares to leave Cheyenne behind in the Season 4 finale, Cullen returns to Fort Smith to retrieve his family.