Once, from Nagasaki toward Edo, sugar was carried along this highway. The town where that culture of sweetness took root flourished in time as the center of Chikuho, which dug out coal. The coal capital greatly changed the composition of its population through a great merger in which five municipalities became one. Iizuka’s numbers are the record of a town in which the highway of sugar and the rise and fall of coal overlap.
A city that opens in a basin through which the Onga River flows, in the central part of Fukuoka Prefecture. The population moved from the former Iizuka City’s 79,365 in 2005, before the merger, to 131,492 in 2010, after the merger, and then to 126,364 in 2020. What I (Atlas) want to read here is not the sign "a coal town," but the causal thread: how the history — the Nagasaki Road, the Chikuho Coalfield, the great merger — is translated into today’s population and finances.
01 · Seeing the present Iizuka in its numbers
In the latest Population Census the population is about 126,000 (126,364 in 2020). This city’s population has a large step from a merger. In 2006 Iizuka City merged with four surrounding towns to become the present city area. Before the merger it was the former Iizuka City’s 80,651 in 2000 and 79,365 in 2005, but by 2010, with the four towns added, it had risen by more than fifty thousand to 131,492. From there, to 129,146 in 2015 and 126,364 in 2020, it has declined gently after the merger.
Looking inside, the figure of a central city of Chikuho appears. The share aged 65 and over rose from 19.5% in 2000 to 31.4% in 2020, passing three in ten. The household-with-children share is 19.4% (2020), and the Childcare Waitlist was zero in both 2024 and 2025. The Fiscal Capacity Index was 0.49 in fiscal 2023 — its own tax revenue does not reach half of expenditure, and its dependence on the allocation tax is large. A coal capital, losing population and deepening its aging after widening the city area by a great merger, keeps a zero waitlist. Why this combination arose does not come into view without reaching back to two pasts — the Nagasaki Road and the Chikuho Coalfield.
Source: Population Census (Statistics Bureau, MIC) / Local Government Finance Survey, Fiscal Capacity Index (MIC) / Childcare Facility Status Report (Children and Families Agency) / Real Estate Information Library (MLIT)
02 · The sugar road of the Nagasaki Road, the center of the Chikuho Coalfield, the merger of one city and four towns — the history behind the numbers
Iizuka’s skeleton is set by the geography of a basin through which the Onga River flows and by two histories — a highway and coal. The older layer is the highway. In the Edo period the Nagasaki Road, linking Nagasaki and Kokura, passed through this land. This highway was also the road by which the sugar brought to Nagasaki was carried to Edo, and so is called "the Sugar Road." Along the road, a culture of confections using sugar took root, and in Iizuka, too, a noted local confection, known in many places, was born. As a post town of the highway, Iizuka first flourished.
And in the modern era, this land became a coal town. From the Meiji era on, this area developed greatly through the mining of coal, as the center of the Chikuho Coalfield. Remains conveying the look of a coal town — such as the mansions of a family that made its fortune in coal — are still many within the city. With the prosperity of the coal industry, a wooden playhouse conveying the kabuki style of the Edo period opened in 1931 (Showa 6) as a place of entertainment. But as energy moved from coal to oil, the mines were closed. From a post town of the highway sugar traveled, to a coal capital that dug out coal. The history of a highway and coal, held by the geography of the Onga basin, has formed the present shape of the town.
Source: Iizuka City (a post town of the Nagasaki Road, the Chikuho Coalfield, the Aso family, the Kaho Theater, the 2006 merger — overview) / An overview of the Kaho Theater (a playhouse opened in 1931 — Iizuka City)
03 · In a coal capital, losing population after the great merger
What characterizes Iizuka is that, while it holds the history of a post town of the Nagasaki Road and the center of the Chikuho Coalfield, it has been losing population gently after widening the city area by a great merger. From 131,492 in 2010, with the four towns added, to 126,364 in 2020, some five thousand were lost over ten years. As a central city of Chikuho after the coal industry finished its role, one can read that, amid a flow of young generations moving to Fukuoka and elsewhere, the population has declined gently. That the share aged 65 and over passed three in ten at 31.4% in 2020 is an expression of that.
On the other hand, the Childcare Waitlist has held at zero. One can read this as an expression of the urban functions of a central city of Chikuho, and of a certain access to Fukuoka, keeping young households tied in place. The Fiscal Capacity Index of 0.49 is a level whose own tax revenue does not even reach half of expenditure, and its dependence on the allocation tax is large. As a town of Chikuho after the prosperity of the coal industry departed, it reflects that the tax source has its limits. The population declines, the aging passes three in ten, and the fiscal stamina is weak. These are things happening at once upon the history of a highway and coal, and one cannot speak of the whole picture of a town of Chikuho by taking out any single number.
Source: Population Census (Statistics Bureau, MIC) / Local Government Finance Survey, Fiscal Capacity Index (MIC) / Childcare Facility Status Report (Children and Families Agency)
04 · A town where the highway of sugar and the rise and fall of coal overlapped
In Iizuka, several functions of differing histories are folded together. One is the old layer of a post town of the Nagasaki Road, along which sugar was carried from Nagasaki to Edo, where a culture of sweet confections took root. Another is its character as the center of the Chikuho Coalfield from the Meiji era on, retaining the look of a coal town and the wooden playhouse opened in 1931. The geography of the Onga basin gives this town the peculiar structure of a central city of Chikuho.
The Nagasaki Road passed through the basin — that condition first called a post town of the highway, and in time drew in the mining of coal. From a post town of the highway sugar traveled, to a coal capital that dug out coal, and then to a central city of Chikuho after coal departed. Layering two histories that finished their roles, this town still sits firmly in the very middle of the Chikuho basin.
Source: Iizuka City (a post town of the Nagasaki Road, the Chikuho Coalfield, the Aso family, the Kaho Theater, the 2006 merger — overview) / An overview of the Kaho Theater (a playhouse opened in 1931 — Iizuka City)
05 · Atlas’s note — a coal capital walking on past a highway and coal that finished their roles
Lay out Iizuka’s numbers and the indicators of a central city of Chikuho line up: a population decline after the great merger, an aging rate of 31.4%, a household-with-children share of 19.4%, and a fiscal capacity of 0.49. But to my eye (Atlas), used to handling numbers, what I want to note first is the fact that the population step is due to the great merger of one city and four towns in 2006. The 79,365 of 2005 is the figure of the former Iizuka City alone, and cannot be simply connected to and read against the 131,492 of 2010 with the four towns added. The increase of more than fifty thousand is not the population increasing, but the result of the city area widening through the merger. It is reasonable to read the slope of decline — some five thousand lost in the ten years after the merger.
Another thing I want to consider is that this town holds two histories — "highway" and "coal" — that both finished their roles. The Nagasaki Road ceded its major role to the age of rail and roads. The coal of Chikuho was dug dry with the energy shift to oil, and the mines were closed. How a town lives on after a once-flourishing industry has finished its role — Iizuka’s fiscal capacity of 0.49 shows the limits of the tax source that a town of Chikuho holds after the prosperity of coal departed. To measure this town, which began as a post town of the Sugar Road and passed through being a coal capital, by the convenience of commuting, by the affordability of housing, or by the environment for raising children — change the scale you apply, and the outline of the town you see changes too. Deep behind the soot-stained memory of coal remains the sweetness of sugar carried from Nagasaki. Behind the hard words "coal capital," this town still lets the trace of an old highway drift in a single bite of a noted confection.
Source: Population Census (Statistics Bureau, MIC) / Iizuka City (a post town of the Nagasaki Road, the Chikuho Coalfield, the Aso family, the Kaho Theater, the 2006 merger — overview) / An overview of the Kaho Theater (a playhouse opened in 1931 — Iizuka City)
Editor’s note: all figures and sources are drawn from official statistics. The prose follows Atlas’s voice, and AI (atlas-handcrafted-reverse-v1 (Daiki 2026-06-02)) handled the shaping of the text. Evaluative or predictive language (such as “a good buy” or “attractive”) is intentionally left out. Revision id: wave12_8