This study measures the effect of Medicaid expansion on emergency department (ED) utilization. It also explores the mechanism through which treatment effects operate. Identification relies on a county‐level Medicaid expansion rollout within California from 2011 to 2013. The results suggest that Medicaid expansion increased ED utilization in California. Every time one individual transferred into the Medicaid program, there emerged one additional ED visit per year. Furthermore, the effect appears to be driven by difficulty accessing primary care. These findings suggest Medicaid expansion may have different effects in different environments, depending on how easily enrollees can schedule appointments. (JEL I13, I18, I38)

中文翻译：

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扩大医疗和应急部门的使用

本研究测量医疗补助扩展对急诊科（ED）利用率的影响。它还探讨了治疗作用的机制。鉴定工作依赖于2011年至2013年在加利福尼亚州进行的县级医疗补助扩展。结果表明，医疗补助扩展可提高加利福尼亚的ED利用率。每次有一个人转入医疗补助计划，每年都会有另外一次急诊就诊。此外，这种效果似乎是由难以获得初级保健所驱动。这些发现表明，医疗补助计划的扩展可能在不同的环境中产生不同的效果，具体取决于注册者安排约会的难易程度。（JEL I13，I18，I38）