This paper develops a method of assessment of market access difficulties with an application to manufactured trade patterns between developing and developed countries. The method also offers a renewal of the assessment of the impact of regional trading arrangements. We use a micro-founded gravity-type model of trade patterns to estimate the impact of national borders on revealed access to Northern markets by Southern producers. This is made possible by the construction and use of a new database. Ceteris paribus, in the nineties, a rich country imports on average 281 times more from itself than from a developing country, only 61 times more when importing from another rich country. Results reveal that those difficulties faced by developing countries’ exporters in accessing developed countries’ consumers are furthermore higher than the reciprocal. Currently, the tariff equivalents of those border effects differ by around 31 percentage points. Those difficulties in Northern market access have however experienced a noticeable fall since the mid seventies. While tariffs still have in general an influence on trade patterns, our estimates suggest that they are not an important component of market access difficulties faced by Southern exporters on Northern markets. The EU, CUSA/NAFTA, ASEAN/AFTA and MERCOSUR agreements all tend to reduce the estimated degree of market fragmentation within these zones, with an expected ranking between the respective impact of these agreements.
