20th century to today
Electricity started replacing steam as an industrial power source in Helsingin maalaiskunta before World War I. The power station Oy Malmin Sähkölaitos Ab was founded in 1910, and another power station was founded in Oulunkylä in the following year. Malmin sähkölaitos, which had reached a central position, bought a lot from Tapanila for its new power plant. Construction of the power plant and distribution grid, led by Gottfried Strömberg, was finished by the end of the year 1910.
The Helsinki-Malmi Airport was built at Tattarinsuo in the Malmi area of Helsingin maalaiskunta in 1936. The soil in the area was very watery and converting it to an airfield was difficult. The airport was taken into use in December 1936. Before this, air traffic in Helsinki had been served by the Santahamina Airport in Santahamina, which was also part of Helsingin maalaiskunta at the time.
During the great annexation of 1946 the municipalities of Huopalahti, Oulunkylä and Kulosaari as well as about a third of the area of Helsingin maalaiskunta were annexed to the city of Helsinki. The rural municipality lost two thirds of its population, including Malmi and Pitäjänmäki. In 1954 some of the areas of Korso in Tuusula and Kerava were annexed to the rural municipality of Helsinki, as well as a small part of Tuusula in 1959. Vuosaari was annexed to Helsinki in 1966.
The population development of Helsingin maalaiskunta grew rapidly after World War II. Tikkurila became the new municipal centre in the 1950s. New residential areas consisting mainly of detached houses developed among the main roads and new suburban centres developed along the railways running through the area, such as Rekola, Korso and Koivukylä.
In 1952, the new international airport of Helsinki opened in Helsingin maalaiskunta for the 1952 Summer Olympics, leading to the rural municipality becoming an important transport hub. The new airport split the municipality in half and brought large amounts of traffic and industry to its surroundings. The airport has become a significant part of the cityscape of Vantaa, and even today Vantaa is known abroad as an aviation city.
Because of World War II, many new urban areas had been born in Vantaa already in the 1940s, populated mainly by evacuees from Finnish Karelia and frontline soldiers, as well as Helsinkians seeking a less densely populated area to live in. The first apartment building groups were built in Tikkurila, Satomäki and Vaarala in the 1950s, after which rural flight sped up construction of apartment buildings. In the record year 1970, the population of Vantaa grew by ten thousand people.
The Keimola Motor Stadium was built in 1966 along Finnish National Road 3, opposite the residential area of Kivistö, and remained in operation until 1978. Construction of the new Keimolanmäki residential area in place of the former race track started in the 2010s.
In the early 20th century, the majority of the population of Helsingin maalaiskunta was Swedish-speaking. Afterwards, the rapid increase in the population has brought much more primarily Finnish-speaking population to the city, and today only 3.1 percent of the population in Vantaa are Swedish-speaking.
The roads in Finland were widened in the 1960s and 1970s, and the Ring III beltway was built to connect five national roads with each other. Myyrmäki became a second centre in the area after the construction of the Martinlaakso railway, which also sped up development in southwestern Vantaa. New residential suburbs were born along the main railway in the 1960s to 1980s, sped up by rural flight. Areas left outside the main traffic connections, such as Seutula in the west and Sotunki in the east, were left mainly unbuilt and rural-oriented.
In 1972, the municipality was renamed Vantaa (Swedish: Vanda) and promoted to a kauppala (market town) (i.e. Vantaan kauppala/Vanda köping). In 1974, the town got full city rights as Vantaan kaupunki/Vanda stad or "City of Vantaa". The name "Vantaa" comes from the river Vantaa running through the city, along which settlement in the Vantaa area was originally centred. The 650th anniversary of Vantaa was celebrated in 2001.
The city grew rapidly starting from 1960s and a railway line was built to the western side of the city in 1970s.
Since the days of the rural municipality, Vantaa has rapidly developed to its current form because of rural flight and good traffic connections. Like the neighbouring city of Espoo, Vantaa has many suburban commuter towns and lacks a specific city centre. The Helsinki Airport, the busiest airport in Finland by far, is located in central Vantaa.
In 2015, an extension to the existing railway line, the Ring Rail Line opened, providing service to the airport and new residential and working districts. Along the ring road, new residential were constructed. The largest of these developments is the Kivistö suburb followed by the residential districts of Leinelä and Aviapolis. The Ring Rail Line connects the Vantaankoski railway to the Finnish Main Line via the Helsinki Airport at Hiekkaharju.
The annual Beer floating summer event started in Vantaa in 1997. On 11 October 2002, an explosion took place in the Myyrmanni shopping centre in Myyrmäki. Negotiations to resolve the Aceh conflict, led by former President of Finland Martti Ahtisaari, were held in the Köningstedt Manor in Vantaa in early 2005.
To connect the municipality on the west–east, a new tramway is planned to open in 2030. This tramway will run from the Helsinki-Vantaa airport through districts of Pakkala, Aviapolis and Koivuhaka to the administrative centre of Tikkurila and further onward to Hakkila and Länsimäki in the east. The tram will also provide a link to the Helsinki metro at Mellunmäki station. This tramline will be the first tram in Vantaa.