The prediction that the effect of geographic distance as a barrier for trade will decrease over time and eventually be eliminated as a result of technological developments has been proposed for decades. However, empirical evidence suggests the negative effect of geographic distance persists in both international and domestic trade. This study uses data from a national survey of nursery and greenhouse growers in the United States to investigate the effect of geographic distance on trade. We model trades as a two-step process in which selling firms and buyers were matched first, and then a positive trade flow occurs conditional on the match. This process leads to a simple zero-inflated estimation strategy and provides a meaningful interpretation of the zero-trades. We demonstrate that this approach predicts the overall trade flow better than the Poisson or Gamma Pseudo Maximum Likelihood (PML) approach, due to its ability to predict zero trade flows more accurately. The empirical results indicate the effect of distance on trade volume is large and statistically significant. In addition, firms trade almost exclusively with partners in the home state or in states with branch offices. We find that social media and website advertising is much less effective in increasing the trade flow than traditional advertising channels. [EconLit Citations: Q17, Q13].

中文翻译：

---

地理距离对国内贸易的影响：以美国绿色产业为例

关于地理距离作为贸易壁垒的影响将随着时间的推移而减少并最终由于技术发展而被消除的预测已经提出了几十年。然而，经验证据表明，地理距离的负面影响在国际和国内贸易中都存在。本研究使用来自美国苗圃和温室种植者的全国调查数据来调查地理距离对贸易的影响。我们将交易建模为一个两步过程，其中销售公司和买家首先匹配，然后在匹配的条件下出现正的交易流。这个过程导致了一个简单的零膨胀估计策略，并提供了对零交易的有意义的解释。我们证明，这种方法比泊松或伽玛伪最大似然 (PML) 方法更好地预测整体贸易流，因为它能够更准确地预测零贸易流。实证结果表明，距离对贸易量的影响很大且具有统计学意义。此外，公司几乎只与母州或设有分支机构的州的合作伙伴进行贸易。我们发现社交媒体和网站广告在增加贸易流量方面的效果远不如传统广告渠道。[EconLit 引文：Q17、Q13]。公司几乎只与母国或设有分支机构的州的合作伙伴进行贸易。我们发现，社交媒体和网站广告在增加贸易流量方面的效果远不如传统广告渠道。[EconLit 引文：Q17、Q13]。公司几乎只与母国或设有分支机构的州的合作伙伴进行贸易。我们发现社交媒体和网站广告在增加贸易流量方面的效果远不如传统广告渠道。[EconLit 引文：Q17、Q13]。