heterogeneous across export industries. Finally, sunk costs of entry in foreign markets attenuate the negative effect of import uncertainty on survival rates as firms delay exiting the export market. Our results show that neither the mean nor the median time to import impacts survival while our measure of uncertainty captured by the interquartile range leads to highly significant results with regard to export survival. This powerful finding highlights the distinctive effect of uncertainty on export performance. Our findings are robust to the inclusion of other measures of domestic trade costs associated with the import process, including cumbersome formalities to import, ease of access to finance and corrupt practices at the border, confirming the distinctive impact of our measure of import uncertainty on firm export dynamics. Our results suggest that developing countries seeking to promote the survival of newly-exporting firms in foreign markets should consider undertaking policies targeted at reducing the uncertainty these firms face when importing their production inputs.

The remainder of the paper is organized as follows. Section 2 describes the import process, introduces the dataset and provides stylized facts. Section 3 specifies the econometric model and presents the results. Section 4 discusses the quality of our measure of import uncertainty as well as endogeneity concerns. Section 5 concludes.

# **2 Data**

## **2.1 Import Uncertainty**

Following harmonization efforts promoted by international organizations, including the World Customs Organization (WCO) and the Word Trade Organization (WTO), the import process from the moment the cargo arrives at the border post until it is cleared by Customs is relatively standard across countries (Figure 1). This standardization was key to reducing the complexity of the process, as close to 100 steps must be performed by multiple public and private stakeholders, with each step being a potential source of delay.<sup>7</sup> Taking the maritime transport case as an example,<sup>8</sup> the first step is the arrival of the vessel at the port of entry. At this stage, congestion at port terminals can lead to berthing delays with vessels waiting hours or sometimes even days in the queue, and with delays being charged by the shipping company to the importer through higher shipping rates. After berthing, port operators unload the vessel and place its cargo in a shipyard or warehouse while the importing firm or its representative, the Customs broker, verifies the cargo content (e.g., looking for possible inconsistencies); and prepares Customs documents, import licenses, Sanitary and Phytosanitary (SPS) certificates and permits if applicable,<sup>9</sup> filled in electronic or paper form depending on Customs and other border control agencies’ use of Information Technology (IT) systems. In many countries, SPS agencies and Customs require separate declarations, with significant data gathering and task duplication for the importer or its delegate that can be a source of delays. Insufficient container placement capacity or gantry cranes, poor efficiency of port operators during cargo movement or the low celerity with which the importer or the Customs broker

> 7 See for instance the Colombia time release study.

> 8The import process remains similar for other transport modes.

> 9Import licenses are required for goods subject to import quotas, import prohibition (e.g. arms, chemicals) or sanitary and phytosanitary measures (e.g., agricultural goods, food, forestry, cosmetics, pharmaceuticals, etc.).

5