The Øresund Region ( ; ), also known as Greater Copenhagen for marketing purposes, is a metropolitan region that comprises eastern Denmark and Skåne in southern Sweden. Centred around the Øresund strait and the two cities which lie on either side, Copenhagen in Denmark and Malmö in Sweden, the region is connected by the Øresund Bridge, which spans the strait at its southern end, and the HH Ferry route between Helsingør, Denmark, and Helsingborg, Sweden, at the narrowest point of the strait. The Capital Region of Denmark and Region Zealand constitute the Danish side, while Scania constitutes the Swedish side. The region has a population of 4,002,372 (2018) and a population density of . Since the Treaty of Roskilde of 1658, Scania () has been subordinate to the King of Sweden, except during the Scanian War (1676–79) and briefly in 1710, but it only became a province of Sweden under the Treaty of Stockholm 1720 (dated 3 July 1720). From 800 to 1658, Greater Copenhagen was united under the flag of Denmark, although in the early years Denmark sometimes had several local kings. In recent years, part of the population has stressed Scania's regional identity again. The Øresund Region consists of both rural and urban areas. Areas on the periphery of the region have a relatively low population density, whereas the two metropolitan areas of Copenhagen and Malmö are two of the most densely populated in Scandinavia. Helsingborg also forms an important urban hub on the Swedish side. Cross-border activity The Øresund Region is an important hub for economic activity in Scandinavia. In 2007, almost 25 million people traveled over the Øresund Bridge: 15.2 million by car and bus, and 9.6 million by train. By 2009, the figure had risen to a total of 35.6 million travellers by car, coach, train or ferry. Statistics compiled in January 2007 show 14,000 people commuting each day over the Öresund Bridge. Compared with 2005, the commuter traffic increased by 43% in 2006. The growing number of Swedes commuting in order to take advantage of the need for labour on the job market in Copenhagen and the higher salaries offered in Denmark, as well as an increased immigration of Danes to the south of Sweden, were essential factors in the traffic increase. In 2006, 4,300 persons moved from the Danish part of the Øresund Region to Scania, attracted by lower Scanian real estate prices.