Omaha, Nebraska is 2.9 times larger than Fargo, North Dakota.
Area: 120 km2 calculated
Fargo is the largest city in the State of North Dakota, accounting for nearly 16% of the state population. Fargo is also the county seat of Cass County. According to the 2013 United States Census estimates, its population was 113,658. Wikipedia
Area: 342 km2 calculated
Omaha is the largest city in the state of Nebraska, United States, and is the county seat of Douglas County. It is located in the Midwestern United States on the Missouri River, about 10 miles north of the mouth of the Platte River. Wikipedia