As early as the 6th century, the mouth of the Salaca was a Liv settlement known as Saletsa. In 1226 Bishop Albert of Riga built a fortress Salis or Salismünde here, but by the 18th century, it had been completely destroyed by war. Even into the 19th century, the village remained remote and poor, until the construction of a port and shipping industry in the 1870s vitalized the village. A harbor and pier were built, and the mouth of the Salaca was dredged to allow greater shipping access. For a short time Salacgrīva was northern Vidzeme's chief port, handling exports such as grain, flax, and wood for transportation to either Riga or Pärnu. Over 200 ships a year called port at Salacgrīva.
By the beginning of the 20th century, Salacgrīva lost its importance. The port of Ainaži to the north outpaced Salacgrīva, and the opening of the Riga-Valka railroad allowed Vidzeme's exports to be shipped directly to Riga. By 1909, only 150 ships called at Salacgrīva per year, mostly for timber floating down the river.
In the first period of Latvian independence (1918–1940) Salacgrīva enjoyed growth and prosperity. The village received its city rights in 1928, and by 1935 there had just under 1,000 inhabitants, employed as port workers, carpenters, merchants, and fisherman. Salacgrīva was Vidzeme's chief fishing center.
Salacgrīva escaped the large confrontations in World War II, but under Soviet power experienced many changes. The fish-processing center was transferred from Ainaži to Salacgrīva, and to facilitate factory output, Salacgrīva's port was entirely rebuilt. New houses were built to accommodate the growing population. By 1990 the population reached 3,000. On the northern bank Fisherman's Park was built, featuring a stadium and open-air amphitheater
