Vote trading among lawmakers (logrolling) can enable political rent-seeking but is difficult to identify. To achieve identification, we explore the rules governing voting for railway projects in the U.K. Parliament during the Railway Mania of the 1840s. Parliamentary rules barred MPs from voting directly for their interests. Even so, they could trade votes to ensure their interests prevailed. We find that logrolling was significant, accounting for nearly one-quarter of the railway bills approved. We also quantify a negative externality to society from logrolling ranging from 1/3 to 1 percent of contemporary GDP.

中文翻译：

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私人利益，公共恶习：十九世纪英国议会中的铁路和伐木

立法者之间的投票交易（logrolling）可以促成政治寻租，但难以识别。为了实现识别，我们探讨了 1840 年代铁路狂热期间英国议会对铁路项目进行投票的规则。议会规则禁止国会议员直接为他们的利益投票。即便如此，他们也可以交换选票以确保他们的利益占上风。我们发现日志滚动很重要，占批准的铁路法案的近四分之一。我们还量化了从日志滚动对社会的负外部性，其范围从当代 GDP 的 1/3 到 1% 不等。