In Roman times, a little village called Arragone existed near where the church of La Salut now stands. This grew into the town called Arraona or Arrahona in the Middle Ages. Another little village was built just on the other side of the river. This second village, called Sabadell, located on a plain, began to grow and its population was about 600 people (152 houses) in 1378. Sabadell was enclosed by a wall, but due to population growth in the 16th century, some houses were built outside the wall. At that time the first textile industries appeared in the town, devoted especially to woolen clothing. The woolen industry grew over the next centuries, and in 1800 the town's population was about 2000 people.
The 19th century brought two important developments to the town: in 1856 the railway arrived, and in 1877 the town was dubbed a "city". In the 1897 census the population of the city was 23,044 people. The city had become the most important producer of woolen clothing in Spain, and these clothes achieved worldwide fame.
The modernisme movement (related to Art Nouveau) had an important influence in the architecture of the city in the early 20th century and distinctive buildings such as the modernista Hotel Suís (1902), Despatx Lluch (1908) and the Caixa d'Estalvis de Sabadell (1915), as well as the Torre de l'Aigua (1918) and the Mercat Central (1930), were built during the first half of the century.
In the early 20th century, Sabadell, with Terrassa, was the textile city par excellence, being the driving force of a territory poor in natural resources. The population was multiplied by eight, its industry boosted, particularly textiles and metals, and its economy was modernized in the service sector. Due to this industrial activity, Sabadell received massive waves of immigration in the 1950s, 1960s and early 1970s leading to uncontrolled urban expansion and the creation of some new neighborhoods such as Ca n'Oriac and Torre-Romeu.
There has always been since those days a rivalry between Terrassa and Sabadell, because both of them wanted to be capitals of the Vallés Occidental, as both were pretty relevant while this rise textile industry. Nowadays, still there are some popular sayings: "Sabadell mala pell" (Sabadell bad skin) and "Terrassa mala raça" (Terrassa bad race).
The growth of industry and population favored the emergence of an important workers’ movement, and Catalanist, socialist and anarchist parties were very influential up until the upheavals of the Spanish Civil War (1936–39). The victory of the Fascist faction in the war was a step backwards for the city, but in the fifties industry recovered and grew once more. Industries needed workers, and many people came from Andalusia, Murcia, Extremadura, Castile and other parts of Spain to work in the textile and metal industry. Again, a new workers’ and Catalanist movement emerged, this time against Francisco Franco’s regime and with the support of the Roman Catholic Church.
Sabadell was the host of some sessions of the
Assemblea de Catalunya, a multi-party organization that brought together communists, socialists, Catalan nationalists, Catholics and others against the Franco regime. The 1973 oil crisis and Franco's death in 1975 meant an important change in Spain and, of course, in Sabadell. The economic crisis compelled the city to diversify its economic activities. New commercial and leisure areas (the Eix Macià) appeared next to the traditional industries, leading to important economic development for the city.