Skipping to the other end of the country...
Helsinki (23 constituencies, quota 20,953)
01: City Centre (
Keskusta,
Centrum)
20,676 (-277)
As the name hints, this is the old centre of Helsinki, including the entire extent of the city before it was made the capital in 1812. The very heart of the city isn't very heavily populated, but the homes that do exist here (mostly in Katajanokka/Skatudden and Ullanlinna/Ulrikasborg) are extremely expensive, so the seat is extremely safe for the Coalition.
02: Punavuori-Jätkäsaari (
Rödbergen-Busholmen)
21,440 (+487)
This is a slightly awkward seat as it's divided in half physically by the Hietalahti/Sandviken bay, with Punavuori/Rödbergen, in the east, being part of the same old-money-dominated urban core as #01, while Jätkäsaari/Busholmen, in the west, is the core of a new development around the former industrial harbour. This doesn't affect voting patterns too much, however, as both of these are right-wing areas, and so the Coalition holds the seat by a good margin.
03: Kamppi-Töölö (
Kampen-Tölö)
21,965 (+1,012)
Most of this seat was built in the mid-to-late 1800s, as expansions to the original city plan, but today they form part of the absolute heart of the city as much as the previous two seats - the seat includes such landmarks as the National Museum, the Parliament building, the "Church in the Rock" at Temppeliaukio/Tempelplatsen, and the Kampinkeskus shopping centre. Again, living here is very expensive, which tends to weed out anyone not reliably voting for the Coalition.
04: Outer Töölö (
Taka-Töölö,
Bortre Tölö)
22,203 (+1,250)
Besides Outer Töölö proper, which as the name implies was built as a continuation of Inner Töölö around the turn of the century, this seat also covers the Olympic Park and the Meilahti/Mejlans area, which includes Helsinki's biggest hospital, the presidential residence at Mäntyniemi/Talludden, and a large housing estate built in the immediate post-war era. This is somewhat marginal while Outer Töölö is solidly blue, so the seat ends up voting for the Coalition as well.
05: Kallio (
Berghäll)
21,826 (+873)
This is the heart of working-class Helsinki, including the headquarters of most of the old labour movement institutions as well as a large area of what was originally workers' homes for the harbour and various associated factories. As with so many other such areas across the West, it's since been gentrified and turned into a middle-class mecca, but it remains quite politically radical - in 2019 it would most likely have voted Green, and this time it went for the Left Alliance by a respectable margin.
06: Sörnäinen (
Sörnäs)
21,151 (+198)
This, I imagine, would be a relatively new seat, although it's possible that Kallio would've been split in half earlier in which case this seat would've been created from its eastern half. It's named for Sörnäinen/Sörnäs, the easternmost of the old working-class settlements, but today its actual economic centre would most likely be around Kalasatama/Fiskehamnen, a new development in the former industrial harbour. Both it and Kulosaari/Brändö, which is part of this seat largely to make up the numbers and because it doesn't fit anywhere else, vote strongly for the Coalition, which along with vote-splitting between Left, SDP and Greens ensures that this ends up a blue district in spite of its location.
07: Pasila-Vallila (
Böle-Vallgård)
22,680 (+1,727)
This is a slightly heterogeneous seat that includes the rest of the old workers' quarters, centred on Vallila/Vallgård, as well as Pasila/Böle, a substantially newer area (the first parts were built in the 1970s, and it's still growing rapidly) centred on Finland's second-busiest railway station, which forms the junction between the lines toward Turku and Hämeenlinna. There's a noticeable political divide between these two areas, with Vallila voting largely for the Left this time while Pasila was SDP-Coalition marginal. I've coloured it in for the Left here, but I think it could equally well go SDP since that party has more equal support across the constituency.
08: Kumpula (
Gumtäkt)
19,414 (-1,539)
The last seat within Helsinki's pre-1946 boundaries is quite mixed, with both small detached homes and high-density housing present, notably around the former Arabia porcelain factory, which is now home to a number of educational institutions. The strong student presence along with spillover from Kallio and surrounding areas makes it a reasonably left-leaning seat - it's yet another likely Green seat from 2019, which once again does not go their way in 2023, largely due to tactical voting for the SDP to keep another party from coming in first place.
09: Oulunkylä (
Åggelby)
17,912 (-3,041)
This seat is pretty much exactly coterminous with the former municipality of the same name, which existed from 1921 until 1946. It's centred on a station along the Helsinki-Hämeenlinna railway, and resembles #08 in many ways, being a socially divided but broadly middle-class area. It lacks the student presence, however, which means it's a textbook SDP-Coalition marginal seat. The SDP narrowly pull ahead in 2023.
10: Haaga (
Haga)
24,530 (+3,577)
Another former suburban municipality centred on a railway station, Haaga is however a bit more thoroughly middle-class, which makes the seat reasonably good for the Coalition.
11: Munkkiniemi (
Munksnäs)
23,424 (+2,471)
Munkkiniemi/Munksnäs proper is one of the wealthiest and most right-wing parts of Helsinki outside the city centre, so although this seat also includes the more marginal areas of Munkkivuori/Munkshöjden and Pitäjänmäki/Sockenbacka, it's still a safe Coalition seat.
12: Lauttasaari (
Drumsö)
19,417 (-1,806)
Lauttasaari/Drumsö is an island that was largely uninhabited until the early 20th century, but quickly got built out after that and today hosts both the motorway and metro line connecting the southern tier of Espoo to Helsinki city centre. It's one of the most heavily Swedish-speaking parts of Helsinki (around 15%) and very thoroughly middle-class and Coalition-voting.
13: Kaarela (
Kårböle)
20,064 (-889)
This seat, whose Swedish name should not be confused with the village in Hälsingland that almost burned down in 2018, is made up largely of working-class suburbs that grew up around the Martinlaakso/Mårtensdal railway line in the 1970s. As you might expect, unlike the rest of northwest Helsinki, it's pretty solid for the SDP.
14: Pakila (
Baggböle)
19,694 (-1,259)
This seat, whose Swedish name should not be confused with the village in Västerbotten which became a byword for stealing lumber from the Crown in the 19th century, is largely made up of small detached houses (
egnahem) whose original residents were overwhelmingly poor (a lot of them evacuees from Karelia) and left-wing. However, that was a long time ago, and the area's location made it extremely desirable for middle-class families looking to buy a home outright in the post-war era. The result was thorough gentrification and an area that is very safe for the Coalition today.
15: Viiki (
Vik)
22,645 (+1,692)
This is another heterogeneous seat that covers both Pukinmäki/Bocksbacka and Pihlajamäki/Rönnbacka, working-class railway suburbs typical of the area, and the Viiki science park, which is home to the University of Helsinki's life sciences campus and a large student population. Although the latter was one of the strongest areas for the Greens in the whole country, it pretty much all voted SDP in 2023.
16: Malmi (
Malm)
21,302 (+349)
Malm was the administrative seat of Helsinge/Helsinki rural municipality until 1946, and the home of the city's first airport. It remains a local centre for northeast Helsinki, with a shopping centre, a hospital, a significant number of schools and a large railway station. Some of the outlying parts of the constituency lean towards the Coalition, but overall it's a reasonably safe SDP seat.
17: Puistola (
Parkstad)
20,364 (-589)
Puistola/Parkstad, as the name implies, was Finland's first garden suburb, founded in 1906. However, the area's growth mainly took off after the Second World War, when a number of new suburbs were built and Puistola itself was redeveloped with a larger proportion of terraces and flat blocks. While Puistola itself votes for the Coalition more often than not, the rest of the seat is SDP-leaning, and that gives them the seat.
18: Laajasalo (
Degerö)
18,228 (-2,725)
Laajasalo/Degerö, Helsinki's other island suburb, is similar enough to Lauttasaari, albeit a bit less right-wing on the whole. Still a reasonably safe Coalition seat.
19: Herttoniemi (
Hertonäs)
21,290 (+337)
Another socially heterogeneous seat, including both older working-class suburbs in Herttoniemi proper and Roihuvuori/Kasberget and the newer, more middle-class development of Herttoniemenranta/Hertonäs strand. Likely would've been a Green/Coalition marginal in 2019, but in 2023 the SDP win it.
20: Vartiokylä (
Botby)
17,395 (-3,558)
Vartiokylä/Botby is home to Itäkeskus, the commercial and administrative centre of East Helsinki as well as the main junction of the Helsinki Metro's eastern leg. There's not much else notable about this seat, except the fact that I couldn't get it within a reasonable distance of quota - the bulk of the population lives on post-war housing estates, where the SDP leads by quite a margin and the Finns usually come in second.
21: Kontula (
Gårdsbacka)
23,533 (+2,580)
This is perhaps the most homogeneously working-class seat in all of Helsinki, largely covering housing estates built alongside the Metro in the 70s and 80s. It also dips north to take in Jakomäki/Jakobacka, the only area in the city where the Finns seem to be consistently on top. They probably get in second across the seat, but it's likely to be a distant second.
22: Vuosaari (
Nordsjö)
19,970 (-983)
Only ceded to Helsinki in the 1960s and left mostly unexploited until the 90s, the Vuosaari/Nordsjö area is a bit less proletarian than the rest of East Helsinki, but the SDP's growing pull on the liberal middle classes means the seat still ends up voting for them by a good margin.
23: Mellunmäki (
Mellungsbacka)
21,066 (+113)
We're closing things off with another "leftovers" seat, which includes its namesake district, a working-class housing estate that forms the endpoint of the Metro's northeastern branch, as well as a bit of northern Vuosaari/Nordsjö, Vartioharju/Botbyåsen, a more middle-class area that I detached from Vartiokylä to make up the numbers, and of course, Östersundom, the area controversially ceded from Sipoo in 2009 which remains largely rural in spite of repeated proposals to build on it (which is why it was ceded in the first place). Östersundom and Vartiokylä both voted for the Coalition, but they're smaller than Mellunmäki and north Vuosaari, so the seat ends up going to the SDP.
Subtotal
SDP 11
Coalition 10
Left 2
This is in spite of the Coalition topping the polls across the city by a five-point margin - however, their votes tend to be much more concentrated in wealthy areas, so I don't think the wrong-winner result is necessarily unrealistic.
National total (thus far)
SDP 23
Coalition 19
Centre 19
Finns 19
SFP 5
Left 2