Five Midwestern states were studied—Iowa, Nebraska, Minnesota, North Dakota, and South Dakota— along with participants from Manitoba, Ontario, and Saskatchewan.
The project split into independent studies for each region due to a lack of funding, and Harold B. Allen was named director of the Minnesotan atlas.
Fieldwork for LAUM originated as a study of Minnesota folk speech that would join research for the Linguistic Atlas of the North and Central States (LANCS) but shifted into a study covering additional midwestern states.
The project, beginning in 1947, would cover linguistic variation from New England and Atlantic English as settlers moved west in the 19th century.
Some included additional notation consistent with other linguistic atlases to label forms of data collection.
Volume III focuses on charting linguistic maps and exploring phonological variations.
The movement, originating in the most northern parts of New England and the Pennsylvania-New Jersey border, respectively, passed through Ohio and Illinois to the Midwestern states.
Overall, LAUM presented fewer quantitative variations than its predecessors, and many lexical changes derive from the existing lexicon.