The US trade concessions were uniform across all countries eligible for AGOA, but differed for apparel and non-apparel items. For non-apparel, approximately 1,800 items were added to the list of products with zero import duty under the existing Generalized System of Preferences (GSP). As a result, for AGOA countries the number of goods on the US GSP list expanded from 4,600 to more than 6,400 items, defined using the 8-digit HS (Harmonized System) product classification . We will refer to these newly added items as GSP products, for brevity.<sup>7</sup> As soon as a country is declared AGOA eligible, it can export any of these items duty-free to the United States.

For apparel, duty-free access to the US market for exports of an African country is not automatic when AGOA-eligibility is granted. Countries needed to be specifically declared to be eligible for the ‘apparel provision’; the first ones were Kenya and Mauritius on January 18, 2001, three months after most countries were admitted to AGOA proper. Countries have been ‘admitted’ to the apparel provision at various times over the subsequent years. The apparel provision allows for duty-free and, importantly, also quota-free access to the US market for most apparel products, provided that the fabric (or yarn or thread) comes either from the Unites States or from an AGOA country. While the country-level quotas have been removed, a regional (AGOA) quota remains for apparel that was initially set at 1.5% of U.S. imports, but was increased to 3.5% over an 8 year period. These caps were doubled under a set of amendments, called AGOA II, and the new set of caps have not proved binding.

In addition to the governance provisions required for general admission to AGOA, countries seeking access to the apparel provision must prove that they have an effective visa system to verify and enforce the source of the fabric or yarn used in apparel production. Once countries qualify for the apparel provision, they can also be considered for the ‘special rule’ for apparel. This was designed for ‘lesser developed’ AGOA countries, and allows them to source their fabric or yarn from anywhere in the world.<sup>8</sup> While the set of products that benefitted from the trade liberalization (eligible products) was uniform across eligible countries, it was not comprehensive. AGOA applied selectively to both countries and products, but not to all countries, nor to all products. This feature allows us to estimate the effects of the Act on export performance very flexibly using a triple difference-in-differences approach that is discussed in greater detail below. The results we present extend the estimates of Frazer and Van Biesebroeck (2010) to the more recent period. We also use a second identification strategy to verify the robustness of the earlier estimates.

Gibbon (2003) confirms the significant supply response found in Frazer and Van Biesebroeck (2010), for the clothing sector in particular. He emphasizes, however, that not all failing to implement a peace plan and re-entered in October 2011. As of December 22, 2017, the following countries were still excluded from AGOA: Zimbabwe, Somalia, Sudan, South Sudan, the DRC, Equatorial Guinea, Mayotte and Togo.

> 7 Note, however, that there are an additional 4,600 products on the GSP list for which nothing changed after 2000. In our estimation strategy, the inclusion of both country-product and product-year interaction fixed effects implies that products already on the GSP list (for which market access did not change) will not contribute to the estimation of the export elasticity of interest.

> 8 In practice, this is defined as having a per capita GNP below $1500 in 1998, as measured by the World Bank. During our sample period, South Africa was the only country ever eligible for the apparel provision that did not qualify for the special rule (either by rule or exception granted).

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