The Migration History Project is unique in that it tracks the same individuals over a 25-year period, from age 15 to 40. This means following them from before they begin their “own” moves until they have largely completed their relocations. The result is a more comprehensive picture of migration than fragmented annual statistics can provide. Each person is followed from their childhood municipality, first living at home, then moving out, and possibly moving again – or even returning.

The main pattern remains consistent across reports, with a nearly uniform variation by centrality class. Centrality class 1 stands out with the highest net in-migration, while class 6 remains firmly at the bottom. Immigrants are becoming increasingly important. Although most settle in the most central regions, their impact may be even more important in rural areas, where they help offset negative trends. Ukrainian refugees are also visible in the cohort analyses.

In addition to centrality classes, analyses are conducted for the Special Effort Zone in Finnmark and Northern Troms, as well as Norway’s four largest cities. As in the previous report, municipalities in the Effort Zone perform better than comparable municipalities elsewhere, suggesting that targeted measures are effective. The large cities, unsurprisingly, show greater net in-migration than the rest of the country, with Oslo clearly in first place. Oslo also differs from the other cities in that more of the original 15-year-olds remain, even though out-migration – and eventually net out-migration – continues. In the other major cities, return migration and new arrivals eventually balance the outflow.

A central point of the report is to demonstrate two different ways of measuring migration. The traditional method measures outcomes at the end of the period, i.e., the status of the cohort when the original 15-year-olds reach age 35. The new approach measures the total number of residence years the cohort has “left behind” in a municipality from age 15 to 40. The logic is that there is a difference between someone moving out at age 16 versus age 39, and this difference should be reflected in descriptions of migration patterns.

If measurement is based only on the number of people residing in a municipality when the cohort reaches age 40, those who lived there earlier but later moved out become invisible.

For example, only 20 percent of the 15-year-olds who lived in a municipality with centrality class 6 in the year 2000 remained in class 6 throughout the 25 years until 2025, when they turned 40. Sixteen percent had returned, while 64 percent had moved out and not come back. As a result, the out-migrants had, on average, lived more years in class 6 than those who stayed. Collectively, those who eventually moved away were more significant to their home municipality over the 25 years than those who remained, since they had lived there for some years before leaving.

If one looks only at the end situation, when all the out-migrants are gone, they appear merely as history, with no relevance for the future.

The main purpose of this report is therefore to highlight the importance of the temporarily settled – out-migrants and in-migrants who later moved away – when analysing cohort migration patterns. This has been done for the centrality classes, the Effort Zone in Finnmark and Northern Troms, and the cities of Oslo, Stavanger, Bergen, and Trondheim.