The last meter-gauge and narrow-gauge steam locomotives in regular service were retired in 2000. After being withdrawn from service, most steam locomotives were scrapped, though some have been preserved in various railway museums. The only steam locomotives remaining in regular service are on India's heritage lines.

Yes, steam locomotives are considered obsolete for mainstream commercial and freight rail transport. However, the answer is nuanced, as they still exist in specific niches.

Here’s a breakdown:

Why They Are Obsolete (For Mainline Service):

1. Inefficiency: Steam locomotives are thermally inefficient, converting only about 5-10% of the energy in coal/wood into useful work. The rest is lost as heat and exhaust.
2. High Operational Costs: They require enormous amounts of fuel and water. Operating them demands large crews (engineer, fireman, sometimes more) and extensive, labor-intensive maintenance.
3. Labor Intensity: They cannot be operated by a single person. They need constant attention for firing, water management, ash disposal, and lubrication.
4. Limited Power and Availability: They need frequent stops for water and coal, and spend significant time offline for cleaning and boiler maintenance. They cannot match the sustained power and availability of modern diesel or electric locomotives.
5. Environmental Impact: They are major polluters, emitting large quantities of smoke, soot (particulates), and carbon dioxide. They are not compatible with modern emissions standards.

The transition was so decisive that by the 1960s in most developed countries (and by the 2000s in places like China and India), steam locomotives were almost entirely replaced by diesel-electric and electric locomotives, which are: More efficient (diesel: ~30-35%, electric: even higher). Can operate for days with one crew and refueling. Require less maintenance. Offer superior control