The Trans-Sahara Highway or TAH 2, formally the Trans-Saharan Road Corridor (TSR), and also known as the African Unity Road, is a transnational infrastructure project to facilitate trade, transportation, and regional integration among six African countries: Algeria, Chad, Mali, Niger, Nigeria, and Tunisia. It runs roughly 4,500 km (3,106 mi) north to south across the Sahara desert from Algiers, Algeria on the Mediterranean coast of North Africa to Lagos, Nigeria on the Atlantic coast of West Africa; subsequently, it is sometimes known as the Algiers–Lagos Highway or Lagos–Algiers Highway.

The TSR is one of the oldest and most complete transnational highways in Africa, having been proposed in 1962, with construction of sections in the Sahara starting in the 1970s. In addition to paving and widening existing roads, the corridor includes thousands of kilometres of cable as part of the "Trans-Saharan Fibre Optic Backbone", a multinational project to increase high-speed telecommunications across the region. The physical infrastructure is to be complemented by policies relaxing cross-border trade and migration and developing logistical services.

The TSR is one of nine Trans-African Highways (TAH) being developed by United Nations Economic Commission for Africa (UNECA), the African Union (AU), the Islamic Development Bank (IsDB) and the African Development Bank (AfDB) with the support of the Arab Bank for Economic Development in Africa, UNCTAD, and other regional and international organizations.

As of 2022, the majority of the highway has been complete, with the central section between Algeria and Niger still being paved.