November 1926: "One hundred and six lookout towers have been in operation in Michigan during 1926. During the last four seasons the State has purchased only inclosed towers, at the rate of 20 a year. It is estimated that 150 towers will be needed to put the entire fire district under close observation." (The Forest Worker)
January 1930: "Five new fire towers were erected in the State during the year (1929)." (Forest Worker)