covariates are readily comparable with the corresponding values from the existing literature.<sup>18</sup> This establishes the representativeness of our sample. Turning to the specific covariates, we see that distance is a very significant impediment to international trade. The estimates on _DIST_ are large, negative, and significant at any conventional level for each of the four sectors. According to our results, Agriculture and Mining are the two sectors where the negative impact of distance is the strongest, while the effect of distance on Services trade is the weakest. We find this heterogeneity intuitive and we point to transportation costs as a natural explanation for it.

Consistent with most of the existing gravity literature, we obtain positive estimates of the effects of contiguity and language. In each case, the impact of these determinants of trade is positive in all sectors. However, it is not statistically significant for Mining. A possible explanation for this result is specialization in this natural resource industry. We also obtain positive and statistically significant estimates of the impact of FTAs in each sector, which attest to the important and successful positive effect of trade policies in promoting bilateral trade among FTA members and is consistent with findings from the extensive related literature. According to our estimates, FTAs have been most effective in Mining and least effective, but still important, in Services.

Next, we turn to the estimates of the impact of international borders, which are of central interest to us. We remind the reader that, by construction, our border variables are indicators that are designed to capture the impact of all observable and unobservable barriers to trade that act on international relative to internal trade, after controlling for all standard gravity covariates. Four main results stand out. First, based on the estimates of _BRDR_ from Table 1, we conclude that the average impact of borders on international relative to internal trade is very large and significant. This is consistent with the extensive literature that has studies the effects of borders and home bias in trade.<sup>19</sup> All BRDR estimates are negative and significant at any conventional

> 18For a reference set of gravity estimates, we direct the reader to the meta-analysis indexes of Head and Mayer (2014) and to the disaggregated gravity estimates of Borchert et al. (2021 _b_ ).

> 19For analysis of the effects of borders and ‘home bias’ in the United States see Wolf (2000), Mayer and Head (2002), Hillberry and Hummels (2003), Millimet and Osang (2007), Head and Mayer (2010), Hillberry and Hummels (2012), Yilmazkuday (2012); for the European Union see Nitsch (2000), Chen (2004), and Head and Mayer (2010); for OECD countries Wei (1996); for China see Young (2000), Poncet (2003, 2005), Holz (2009), and Hering and Poncet (2009); for Spain see Llano and Requena (2010); for France see Mayer (2005); for Brazil see Fally, Paillacar and Terrac (2010); for Germany see Lameli et al. (2013) and Nitsch and Wolf (2013); for Canada see Agnosteva, Anderson and Yotov (2019); and Anderson, Larch and Yotov (2018) for the world.

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