Timeline for all types of items produced by
Northwestern Corp. [Morris, IL, USA]

Year	Items
1912	1
1920	1
1925	7
1930	1
1931	2
1933	4
1936	1
1939	5
1940	3
1941	1
1947	1
1949	2
1954	2
1958	1
1960	1
1961	1
1965	1
1966	2

37 items with a valid date were considered for this timeline (88.10% of the total)
5 items with an invalid date.

Help us in our quest to find exact dates for:

191?: 3 items.
193?: 1 item.
196?: 1 item.