Railway lines opened in 2004

METRORail is the 22.7-mile (36.5 km) light rail system in Houston, Texas (United States). In 2024, the system had a ridership of 13,456,400, or about 42,200 per weekday as of the fourth quarter of 2024. METRORail ranks as the second most-traveled light rail system in the Southern United States and the 10th most-traveled light rail system in the United States, and has the highest ridership per mile for light rail systems in the Southern US. METRORail is operated by the Metropolitan Transit Authority of Harris County (METRO).

The Las Vegas Monorail is a 3.9-mile (6.3 km) automated monorail mass transit system located adjacent to the Las Vegas Strip in Clark County, Nevada, United States. It connects several large casinos in the unincorporated communities of Paradise and Winchester just south of Las Vegas city limits. Built at a cost of $650 million, it was privately owned and operated by the Las Vegas Monorail Company until their 2020 bankruptcy. It was then sold to the Las Vegas Convention and Visitors Authority, a local government agency. In 2022, total annual ridership was roughly 4.3 million, down from a pre-Great Recession peak of 7.9 million in 2007. The monorail is a registered not-for-profit corporation, allowed under Nevada law since the monorail provides a public service. The State of Nevada assisted in bond financing, but no public money was used in construction.

The MRT Blue Line (Thai: รถไฟฟ้ามหานคร สายสีน้ำเงิน) or MRT Chaloem Ratchamongkon Line (Thai: รถไฟฟ้ามหานคร สายเฉลิมรัชมงคล) is Bangkok's third rapid transit line, following the Sukhumvit line and Silom line of the BTS Skytrain. It is the first line of the MRT system and is operated by Bangkok Expressway and Metro (BEM). The original 20 km (12.43 mi) MRT Blue Line from Hua Lamphong to Bang Sue opened on 3 July 2004. A 1.2 km (0.75 mi) extension to Tao Poon opened on 11 August 2017. The 15.9 km (9.88 mi) western extension to Lak Song opened for full service on 29 September 2019 and the 11 km (6.84 mi) extension from Tao Poon to Tha Phra to form the quasi loop, opened for full service on 30 March 2020.

The Lynton and Barnstaple Railway (L&B) was a single track, (597 mm) narrow gauge railway. It opened in May 1898 and ran for slightly more than 19 miles (31 km) through the area bordering Exmoor in North Devon, England. Although it opened after the Light Railways Act 1896 came into force, it was authorised and constructed before that act. It was authorised under its own Act of Parliament and built to higher (and more costly) standards than similar railways of the time. It was notable as the only narrow gauge railway in Britain that was required to use main-line standard signalling. For a short period, it earned a modest return for shareholders, but for most of its existence it made a loss. In 1923, the L&B was taken over by the Southern Railway, and eventually closed in September 1935.

The Athens Tram is the modern public tram network system serving Athens, Greece. The system is owned and operated by STASY, which replaced Tram S.A. in June 2011.

The Solothurn–Wanzwil railway was opened on 12 December 2004 to connect with the Mattstetten–Rothrist new line (high-speed line) as part of a package of railways forming Rail 2000.

The Lynton and Barnstaple Railway (L&B) was a single track, (597 mm) narrow gauge railway. It opened in May 1898 and ran for slightly more than 19 miles (31 km) through the area bordering Exmoor in North Devon, England. Although it opened after the Light Railways Act 1896 came into force, it was authorised and constructed before that act. It was authorised under its own Act of Parliament and built to higher (and more costly) standards than similar railways of the time. It was notable as the only narrow gauge railway in Britain that was required to use main-line standard signalling. For a short period, it earned a modest return for shareholders, but for most of its existence it made a loss. In 1923, the L&B was taken over by the Southern Railway, and eventually closed in September 1935.

The Madison Avenue Line is a line of the Memphis Area Transit Authority trolley system. The trolley line began operating in 2004, and cost $56 million to build. It consists of 2.2 mi (3.5 km) of double track along Madison Avenue with six stops stretching into Midtown Memphis. The line was built to connect the Main Street system to the Medical District just east of Downtown Memphis. Trolley service has been suspended since April 2014, after two trolley cars caught fire within a span of six months. Buses have been serving the line since then, but MATA plans to restore trolley operation to the line eventually.

Line 9 is a rapid transit line of the Tianjin Metro. It spans 52.8 km (32.8 mi) with 21 stations, connecting the urban area of Tianjin with Binhai New Area, a new area within the jurisdiction of Tianjin Municipality. The one-way journey time is approximately one hour.

Line 4 of the Shenzhen Metro, formerly branded as the Longhua line, runs South–North from Futian Checkpoint to Niuhu. The line serves Futian District and Longhua District of Shenzhen.