The major achievement of the Economic Community of West African States (ECOWAS) is that it has

The Economic Community of West African States (ECOWAS), established in 1975, aims to promote economic integration and cooperation among its member states. Its major achievement has been widening the market for goods produced within the region.

By reducing trade barriers among member countries, ECOWAS has created a larger regional market that allows goods produced in one member state to be sold more easily across the region. This expanded market benefits producers by giving them access to a larger customer base, which can support economies of scale and encourage greater production and investment.

ECOWAS has not achieved a common currency across all member states. While there have been plans and discussions about a common currency (the Eco), it has not been implemented across the community. The suggestion that ECOWAS increased members' allegiance to former colonial masters is incorrect; ECOWAS was created partly to reduce such dependence and strengthen intra-African cooperation. While ECOWAS facilitates some capital mobility through its protocols on free movement of persons, goods, and capital, this has not been its most prominent achievement compared to the market-widening effect.