Labor Unions and Political Mobilization: Diminishing Returns of Repetitious Contact

Voter mobilization by unions has garnered some attention from scholars, and is seen as an important political tool. Unions often mobilize voters repeatedly across several campaigns; however, the literature treats mobilization as a singular event. This paper empirically analyzes turnout of 85,064 registered voters over 14 months at five election intervals in Los Angeles, exploring whether union-led mobilization is subject to diminishing returns across multiple elections. Results indicate that diminishing returns occur; three or more contacts are no more beneficial than one or two. Contact in recent elections is more effective than distant contact, and results differ slightly by contact type.