Two foot and 600 mm gauge railways are narrow gauge railways with track gauges of 2 ft (610 mm) and 600 mm (1 ft 11+5⁄8 in), respectively. Railways with similar, less common track gauges, such as 1 ft 11+3⁄4 in (603 mm) and 1 ft 11+1⁄2 in (597 mm), are grouped with 2 ft and 600 mm gauge railways.

Most of these lines are tourist lines, which are often heritage railways or industrial lines, such as the Ffestiniog Railway in Wales and the Cripple Creek and Victor Narrow Gauge Railroad in Colorado.

World War I trench railways produced the greatest concentration of 600 mm (1 ft 11+5⁄8 in) gauge railways to date. In preparation for World War II, the French Maginot Line and Alpine Line also used 600 mm (1 ft 11+5⁄8 in) gauge railways for supply routes to the fixed border defenses.

Australia has over 4,000 kilometres (2,500 mi) of 2 ft (610 mm) gauge sugar cane railway networks in the coastal areas of Queensland, which carry more than 30 million tonnes of sugarcane a year.

Many 2 ft (610 mm) gauge and 600 mm (1 ft 11+5⁄8 in) gauge railways are used in amusement parks and theme parks worldwide.

The interchange of rolling stock between these similar track gauges occasionally occurred; for example, the South African Class NG15 2-8-2 locomotives started their career on the 600 mm (1 ft 11+5⁄8 in) gauge. The Otavi Mining and Railway Company in South West Africa (now Namibia) were transferred to the 2 ft gauge railways in South Africa and currently some surviving locomotives reside in Wales on the 1 ft 11+1⁄2 in (597 mm) gauge Welsh Highland Railway and the 1 ft 11+3⁄4 in (603 mm) gauge Brecon Mountain Railway.

• Decauville
• Heritage railway
• Large amusement railways
• List of track gauges
• Minimum gauge railway