Suisun City was established as a shipping port for grain from the surrounding valleys to other destinations for sale or consumption. As with the other cities in Solano County, it originated around 1850.
Below are a couple of selections about the history of Suisun City that were found on a now-discontinued webpage. 
Selection 1:
Suisun City was originally an island, its slough the head of navigable waters down which the grain crops of the valleys to the north were shipped. For grain was the great output of the state in 1850, when Curtis Wilson and Dr. John Baker first sailed up these waters and made a landing at what is now Suisun City. Wild grain and tules surrounded the place and the stay of Wilson and Baker was short. Captain Josiah Wing, with his good schooner, the Ann Sophia, was the first to develop the place commercially. He sailed up the slough in 1851, and in the following year built a warehouse. Wagons drawn by sixteen mules brought the wheat down from the northern country to be stored there between the Ann Sophia’s trip, and by 1854, the place had developed to an extent which warranted Wing and John Owen laying out a town site. Owens and A. W. Hall ran the first store.
Today, sitting back from Main Street is the Lawler House. It was built in 1857 as a ranch house and went through four owners before John Lawler bought and remodeled it in 1947 as a summer home. It was moved to its current location in 1980, from the ranch to Main Street by barge. It is now a museum and sits in the midst of many restaurants and the theater, as well as other businesses along the wharf. On a recent Sunday morning, there was laughter and spirited conversations all around it, mixing the past and presence.
Lawler House, 718 Main Street, Suisun City, CA
Selection 2:
Suisun and Fairfield are on the main line of the Southern Pacific Railroad, and like other towns in Solano, they are also on the state highway. Then, too, the position of Suisun at the head of water navigation, Suisun Channel as it is now known, makes a very low competitive freight rate, something which is of extreme importance when it is remembered that the town has contiguous to it the rich Suisun Valley of 30,000 acres, with its wealth of fruit trees. Cattle and sheep ranges, grain farms and a rich dairy country contribute to the wealth of this portion of Solano.
Today, the railroad station is the second depot to serve these towns. The original station was built when the California Pacific Railroad built the region’s first rail line. The first train ran from Vallejo to Suisun City in 1868. In 1906 there was a fire that not only destroyed the first station, but half of the city’s residential quarter as well. The current station was built in 1914 at a location closer to other forms of transportation.
For more history of the train station, see this link.
For information about the Suisun City, see this link