Thousands of commuters across the region were affected by strike action as RMT union members staged their latest walk-out in the row over driver only operated trains.
Services were disrupted throughout the day with a second day of strike action scheduled for tomorrow.
Bus replacement services were operated on some routes.
Northern advised travellers to allow extra time for their journeys and to check ahead to see if their service is running.
A spokesman for Northern Rail said: “We expect trains and any replacement buses we operate will be extremely busy.
“Please allow extra time for journeys, plan carefully and consider whether travel is necessary.
“If you travel on a strike day and experience a delay of 30 minutes or more to your journey, you are eligible to compensation through Northern’s Delay Repay scheme.
“Northern season ticket holders can also claim compensation on the days they do not travel using this process.”