European route E4 stretches 1,590 km with most of Sweden's length between Helsingborg in the south, and Haparanda in the north, extending less than a kilometre beyond the Finnish border at Tornio.
The E4 is Sweden's most important highway, passing through or by fifteen of Sweden's thirty largest cities, most of them being historically important. It is the second longest road within a single European Union country, behind the E45 between Gothenburg and Karesuando; the E6 through Norway is much longer, but outside the EU.
E4 is also used by Norwegians to drive between Finnmark and Southern Norway, considerably shorter than E6.
The leg between Helsingborg and Stockholm used to be served by Riksväg 1, "Riksettan" ("National Road 1") before the E-number introduction 1962, then with very little motorway.
The E4 is a remnant of an obsolete route numbering standard. With current standards, longitudal highways should have odd numbers. The E4 was to be part of E55, which stretches from Kalamata in Greece to Helsingør in Denmark. Due to the cost of sign replacement, and tradition, Sweden has got permission to retain the numbers E4 and E6.
Most of the E4, except in Norrland, is limited-access highway (motorway in British English). E4 in Norrland is often a 2+1-road with a middle barrier and grade-separated exits.
National rail carrier SJ runs rail traffic parallel to the E4 (often some distance away from it), from Malmö to Stockholm, and onwards from Stockholm to Luleå.
To travel north to south, go to Tornio in Finland, and cross the border. The E8 connects Tornio to Tromsö and Turku.
If you travel to or from Norrland, you should avoid passing through the congested highways in Stockholm at least in rush hour, and instead use roads 50, 55 or 56 through inland Sweden. These roads are non-expressways. Traffic is usually lighter.
The E4 through Stockholm can be congested all the way between Södertälje and Arlanda, especially at rush hour in mornings and late afternoons. The passage through Stockholm requires congestion tax (see Stockholm#Get around).
Though the coast of Norrland is known for its natural beauty, much of the E4 stretches through inland forest. If you have time, consider driving along smaller roads along the sea instead.
The E4 is more known for convenience, than for its beauty. Much of the distance goes through repetitive forests, except some legs; north of Jönköping there is an astounding view of lake Vättern, and the passage through Stockholm is great, provided you don't get stuck in a traffic jam. If you have plenty of time, you should consider parallel routes (but check out which one to use, or you might only see forests anyway)
Cross the border to Tornio. E4 is preferably used for at least one of the directions when visiting Norrbotten, Finnish Lapland or Finnmark.
See Driving in Sweden. Winter driving and animal collisions are significant risk factors, especially in the north.