Originally standard gauge, the railways of the then Cape Colony changed to narrow gauge 3 ft 6 in (1,067 mm), sometimes known as Cape gauge, for cost-cutting reasons.

The railway gauge across Africa is notably inconsistent, a legacy of different colonial powers. The most common gauge is the Cape Gauge (1,067 mm or 3'6"), which is the standard for most of Southern and Central Africa, including South Africa, Zimbabwe, Zambia, and Nigeria's older lines. However, much of East Africa (Kenya, Uganda, and Tanzania) historically utilized Metre Gauge (1,000 mm). In recent years, including through 2026, there has been a massive shift toward Standard Gauge (1,435 mm) for new, high-speed regional projects. For example, Kenya’s Standard Gauge Railway (SGR) and Nigeria's modern links between Lagos and Abuja use this wider, more modern standard to allow for faster trains and heavier loads. This "gauge gap" remains a significant challenge for trans-continental rail integration, as cargo must often be physically moved between trains when crossing borders where the track widths change.