one. Second, we set the depth of non-mapped RTAs as the value of the closest-in-time (positive) RTA depth observed for the considered country-pair.

The Exporter Dynamics Database (EDD) takes the form of multiple databases: one per country.<sup>8</sup> So, as a last step in the construction of the final data set, each country-specific EDD is merged with the CEPII gravity database. Finally, we merge the tariffs data from MacMap (CEPII), and pool all the 55 country-specific databases to get a single proper and complete firm level base. This dataset initially contains 29,009,865 observations (firm-destination-productyear specific) spanning from the late 1990s to 2020. However, the DTA database covers only the period 2000-2020; so we keep only firm export data over that period. It must be noted that the coverage of the EDD varies by country: for some countries we have data for the entire 2000-2020 period, for some other countries we have a more limited time period (cf. table A1 in appendices). Although original firm-level exports data are (also) product (HS6) specific, our main variable of interest is not, so we aggregate (sum) export data by firm-destination-year across HS6 products.

As described in Table 1, the majority of exporters included in the EDD have at least one active RTA in force (i.e. 48 out of 55). However, only a sub-sample of countries (and countrypairs) have changed the depth of their RTAs in the period 2000-2020 (i.e. a newly signed RTA or amendment of pre-existing RTAs). Namely, 31 exporting countries signed new RTAs or amended a pre-existing one, giving _within_ variation to our measures of RTAs depth. This translates into 701 country-pairs having time variation in the depth of RTAs in the period 2000-2020. This time variation comes mainly from the entry into force of new trade agreements.<sup>9</sup> Since in the empirical strategy we rely on the within country-pair variation in RTAs’ depth, the final estimation sample considers only such 31 exporting countries and contains 4,659,362 observations with non-missing information on export value and content of RTAs. The estimation sample shrinks to 2,924,126 observations because of missing values in the tariff data.

Among the 31 exporting countries having _within_ variation in the RTA depth values, 15 countries account for 87% of the overall variation in the RTA depth. These are: Croatia, Georgia, Colombia, Chile, South Africa, Serbia, Slovenia, Peru, Mauritius, Guatemala, Madagascar, Nicaragua, Tanzania, Ecuador, Malawi. In Figure 1 we show the empirical distribution of country-pairs exports (panel a and b) and firm-destination specific exports (panel c and d) for the sub-sample of the 15 countries that provide much of the variation in RTA depth.<sup>10</sup> In panel (a) of Figure 1 we show the empirical distribution of bilateral exports for country-pairs with and

> 8In case of breaks in the firms’ identifiers over the time period covered, the Exporter Dynamics Database contains two separate data sets per country (before _versus_ after the break in the firms’ identifier). In case of breaks in the firms’ identifiers, we keep the most recent period (i.e. after-break period).

> 9In our final sample, 72 RTAs involve more than two members, while 2 are bilateral for a total of 74 agreements contributing to the within variation of our RTA depth variable.

> 10In Figure A2 we provide the same evidence for the full set of 31 countries with time variation in RTA depth.

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