Union membership was about 15% in the 1930's and peaked at about 35% in the 1950's in the U.S. Currently, union membership is about 10%, even though in the past couple of decades, public sector union membership has increased.
Unions, labor movements and workers had specialty newspapers throughout the country. Some of these have been digitized and the links by state are below. Please note that I have excluded subscription databases from the list.
(Updated December, 2020; recently added links are in BOLD)
California
- California Oil Worker
- California Federation of Labor Weekly
- Western Worker
- Organized Labor (San Francisco, 1900-1988)
- Idaho Forester
- Boise, Idaho, 1913-1914 - Idaho labor herald.
- Boise, Idaho, 1914-1917 - The Gem worker and the Idaho labor herald.
- Labor News Review
- Chicago IL Daily Worker
- American Appeal
- American Appeal
- The Communist
- Communist
- Communist
- Industrial Union Bulletin
- Klan Kourier
- Labor Unity
- New Majority
- The Daily Racing Form
- The Sentinel
- Louisville, Ky., 1904-???? - Ohio valley worker : official paper of the Federated Trades Council of Louisville, Trades and Labor Council of New Albany, Central Labor Union of Jeffersonville.
- Freedom's Banner (Marion, Grant County; 25 June 1910 - 6 August 1910)
- Indiana Socialist Party Bulletin (Indianapolis, Marion County; 1 October 1911 - 1 September 1913)
- Indiana Socialist (Indianapolis, Marion County; 22 March 1913 - 12 July 1913)
- Marion Labor Sentinel (Marion, Grant County; 23 April 1914 - 12 November 1914)
- The Marion Socialist (Marion, Grant County; 20 August 1911 - 27 October 1912)
- Des Moines Iowa Unionist (1907 - 1918)
- Iowa Unionist (1906 - 1913)
- Des Moines Iowa Unionist (1907 - 1918)
- Iowa Unionist (1906 - 1913)
- Labor News
- Ohio Valley Worker : Official Paper Of The Federated Trades Council Of Louisville, Trades And Labor Council Of New Albany, Central Labor Union Of Jeffersonville
- Ohio valley worker - (1904-09-10 - 1904-09-10) (1 issue, 4 Pages)
- Labor Journal — Alpena, Alpena County (Mich.) — 3 January 1885 - 26 December 1890
- Michigan Labor Journal — Alpena, Alpena County (Mich.) — 14 June 1884 - 27 December 1884
- Labor Journal
- Michigan Labor Journal
- Detroit Sunday Journal
- The Grange Visitor
- Grand Rapids CIO News
- Grand Valley AFL CIO News
- Grand Valley Labor News
- Work In Progress
- Duluth, Minn., 1896-current - The labor world.
- Duluth, Minn. - Labor leader (5/1/1917 - 10/5/1917)
- Duluth, Minn. - The labor world (1896-04-11 - 12/13/2017)
- Duluth, Minn. - Truth (10/12/1917 - 12/29/1922)
- Minneapolis, Minn. - Allarm (12/1/1915 - 5/1/1918)
- Minneapolis, Minn. - Mississippi Valley lumberman and manufacturer (1876-08-17 - 1887-08-05)
- Minneapolis, Minn. - Teamsters Joint Council 32 (2/1/2016 - 11/1/2018)
- Minneapolis, Minn. - The Minneapolis labor review (1/22/2016 - 12/22/2017)
- Minneapolis, Minn. - The Mississippi Valley lumberman (1887-08-12 - 4/28/1905)
- Minneapolis; St. Paul - Our side (5/20/1915 - 9/9/1920)
- Red Wing, Minn. - The Grange advance (1873-10-15 - 1877-08-01)
- St. Paul, Minn. - The St. Paul union advocate (1/1/2016 - 12/16/2017)
- Labor Review
- Northwest Organizer
- St. Paul Union Advocate
- Fighting Worker
- Daily Worker
- Labor Action
- Workers Age Lovestone
- New York, N.Y., 1907-1970 - Radnička borba = Workers' struggle.
- E.J. Workers Review
- E.J. Workers Magazine
- New York City - Daily Worker 1924-1926
- New York City - Workers Age 1932-1940
- New York City - Workers Challenge 1922
- Cincinnati, Ohio, 1912-1937 - The labor advocate.
- Cleveland, O. [Ohio], 1911-1920 - Echo : Wochenblatt der Vereinigten Deutschen Socialisten Clevelands.
- Cincinnati - Labor Advocate - 1915-1917
- Cleveland - Echo : Wochenblatt der Vereinigten Deutschen Socialisten Clevelands - 1911-1920
- Cleveland - Toiler - 1920-1921
- Cleveland - Americké Dělnické Listy (American Workingmen's News) - 1918-1941
- Cleveland - Enakopravnost - 1942-1947
- Cleveland OH Ohio Socialist
- Ohio Socialist
- Dayton, Ohio, 1940-1944 - Dayton union news. [volume]
- Dayton - Dayton Union News - 1940-1943
- Youngstown - Bulletin - 1919-1977
- Cleveland - Radnička Borba = Workers' Struggle - 1941-1946
- The Labor Review - 1
- The Labor Signal - 187
- The Lincoln County Socialist - 2
- Oklahoma Labor Unit - 375
- Oklahoma State Labor News - 123
- The Social Democrat - 43
- The Socialist Antidote Independent - 17
- The Union Labor Bulletin - 1
- Muskogee Labor Amalgamator
- Richmond, Va., 1885-18?? - The Labor herald.
- Labor Herald (Richmond, VA, 1886)
- Riverside (Shenandoah Iron Works, VA, 1880)
- Pacific Fisherman Journal
- The Washington Socialist
- Puget Sound Chemist
- Industrial Worker
- The Northwest worker.
- The Northwest worker
- The labor journal.
- The Labor journal
- The Labor Press Project - Pacific Northwest Labor and Radical Newspapers
- The Washington socialist
- The Washington socialist.
- Agitator
- Hoquiam, Wash., 19??-19?? Southwest Washington labor press.
Good luck finding articles about your union ancestors!