Informal agreement between legislators to vote for each others’ priorities. Logrolling occurs frequently when lawmakers, unencumbered by pressure from party leaders, push through a bill that benefits their constituencies, but is financed by all taxpayers. Popular logrolling projects include, dams, bridges, highways, housing projects and hospitals.
The term originates from the early days of neighbors helping each other clear land to build homes. From Answers.com: “Politicians have long recognized that logrolling is mutually beneficial in legislative halls too. The word was applied to the political practice of reciprocal backscratching as early as 1809.”
According to Julian E. Zelizer, author of “Arsenal of Democracy: The Politics of National Security From World War II to the War on Terrorism”, former president Johnson was an expert in the politics of logrolling: “… direct persuasion could go only so far. Johnson was also a big believer in using logrolls to obtain a vote.”