I saw this on FamilySearch recently – Build Your Norwegian Family Tree with Bygdebøker: https://www.familysearch.org/blog/en/bygdeboker-norwegian-research/. Article is a bit longer, but here are some details. If you have Norwegian ancestry, worth checking out.
November 18,2020 by Sunny Morton
Until about 1900, most Norwegians lived in rural areas, where farming was the way of life for hundreds or even thousands of years. They tended to live in solitary homesteads scattered across the landscape, rather than clustered together in villages.
The bygdebøker give information about the people living on the farms in these communities as well as a history of the communities themselves. Rural communities or districts, called bygds, often encompassed numerous farms. Over time, each bygd experienced a unique history. Families, who often lived on farms for many generations, had their own stories. So did the land, as it cycled through seasons of plenty and want. Local history unfolded in each bygd’s churches, schools, courts, and community gatherings.
Gathering the History of Bygds
In the early 1900s, the Norwegian Historical Association began a significant, ongoing effort to document the history of each bygd. They laid the groundwork as local historians began researching the histories of farms and local communities. The writers compiled narratives from parish records, legal records (such as tax, court, or estate documents), and other historical sources as well as from interviews with residents.
The practice of creating bygdebøker remained strong throughout the 20th century. In 1955, Norway’s parliament established a permanent organization to support the ongoing creation of more community histories, which by then also included urban and regional coverage.