As more products were developed and sales increased, more office and factory space was needed. In 1937, company president William L. McKnight announced a half million dollar expansion program that included Building 20 for manufacturing in 1937-1938 and Building 21 as the new administrative offices in 1939-1940.
Buildings 22, 23, and 24 were built for tape research and manufacturing over the following decade. Building 42 was constructed in 1950-1951 to house the company's expanding office staff, sales departments, and division heads, following a major reorganization in 1948.
As 3M expanded, it acquired properties in the neighborhood and demolished existing houses to provide sites for Building 24, the water tower, and the adjoining parking lot.