Helsingborg is one of the oldest cities of what is now Sweden. It has been the site of permanent settlement officially since 21 May 1085. Helsingborg's geographical position at the narrowest part of Øresund made it very important for Denmark, at that time controlling both sides of that strait. From 1429 Eric of Pomerania introduced the Øresundstolden (the Sound Dues), a levy on all trading vessels passing through the sound between Elsinore and Helsingborg. This was one of the main incomes for the Danish Crown. Crossing traffic, like fishermen, was not subject to the tax, which was initially directed against the Hanseatic League.
The Sound Dues helped Helsingør to flourish, and some of it spilled over to Helsingborg. The northern narrow inlet to Øresund with its relatively high coastlines made impression on many mariners, and when Kronborg during the Renaissance was rebuilt from a fortress to a Palace the area got famous. Evidence of this is William Shakespeare's Hamlet, which unfolds at Kronborg; the titular Prince of Denmark may well have hidden himself from his uncle in Helsingborg. The era of the Renaissance helped the Kingdom of Denmark, but towards the middle of the 17th century, the situation worsened.
Following the Dano-Swedish War (1657-1658) and the Treaty of Roskilde Denmark had to give up all territory on the southern Scandinavian peninsula, and Helsingborg became submitted to new rulers. King Charles X Gustav of Sweden landed here on 5 March 1658 to take personal possession of the Scanian lands and was met by a delegation led by the bishop of the Diocese of Lund, Peder Winstrup. At that time the town had a population of barely 1,000 people. He soon attempted to erase Denmark totally from the map, by attacking Copenhagen but failed (Treaty of Copenhagen (1660)), and died in Gothenburg soon afterwards. Not much changed for some 15 years, but as Charles XI was declared of age, many processes began. As the new king indeed was unsatisfied with his former rulers (Known as "Förmyndarräfsten" in Swedish history).
The new situation, being a border town, caused problems for the town. The days of conflict were not over. Denmark made two recaptures of Scania, but couldn't hold it. The last Danish attempt to regain Scania was in 1710, when 14.000 men landed on the shores near Helsingborg. The Battle of Helsingborg was fought on the 28th of February just outside the city, which was badly affected. It took a long time to recover, and in 1770 the city had 1321 inhabitants and was just slowly growing.
On 20 October 1811 Jean-Baptiste Bernadotte, Marshal of France and crown prince-elect of Sweden (later king Charles XIV John) took his first step on Swedish soil in Helsingborg on his journey from Paris to Stockholm.
From the middle of the 19th century onwards, however, Helsingborg was one of the fastest growing cities of Sweden, increasing its population from 4,000 in 1850 to 20,000 in 1890 and 56,000 in 1930 due to industrialization. From 1892 a train ferry was put in service, connecting Helsingborg with its Danish sister city Helsingør. A tramway network was inaugurated in 1903 and closed down in 1967. Plans are underway to reintroduce trams in the city.