Je vois que les États-Unis ont un système ferroviaire très développé avec plus de 180 000 miles de voies, mais que Amtrak ne dessert pas certaines grandes villes comme Las Vegas et Phoenix. Est-ce que quelqu'un peut m'expliquer pourquoi ils ne desservent pas ces destinations majeures ?
Transportation

The overwhelming majority of roads in the United States are owned and maintained by state and local governments. Roads maintained only by the U.S. federal government are generally found on federal lands (such as national parks) or at federal facilities (like military bases). The Interstate Highway System, with its large, open freeways linking the states, is partly funded by the federal government but owned and maintained by the state government hosting its section of the interstate. Some states fund and build their own large expressways — often called " parkways " or " turnpikes " — that generally use tolls to pay for construction and maintenance. Likewise, some privately owned roads may use tolls for this purpose.

Passenger and freight rail systems, bus systems, water ferries, and dams may be under either public or private ownership and operation. U.S. civilian airlines are all privately owned. Most U.S. airports are owned and operated by local government authorities, and there are also some private airports. The Transportation Security Administration has provided security at most major airports since 2001.

The U.S. Department of Transportation and its divisions provide regulation, supervision, and funding for all aspects of transportation except for customs, immigration, and security. (The latter remain the responsibility of the U.S. Department of Homeland Security.) Each U.S. state has its own department of transportation, which builds and maintains state highways. Depending upon the state, this department might also directly operate or supervise other modes of transportation.

Aviation law is almost entirely the jurisdiction of the U.S. federal government. Vehicle traffic laws, however, are enacted and enforced by state and local authorities, with the exception of roads located on federal property (national parks, military bases) or in the unorganized U.S. territories. The United States Coast Guard is the primary enforcer of law and security on U.S. waterways, inland as well as coastal, but economic jurisdiction over coastal tidelands is shared between state and federal governments. The country's inland waterways are the world's fifth-longest, totaling 41,009 km (25,482 mi).

Of the world's 50 busiest container ports, four are located in the United States. The busiest in the U.S. is the Port of Los Angeles.

Personal transportation in the United States is dominated by automobiles, which operate on a network of 4 million miles (6.4 million kilometers) of public roads, making it the longest in the world. The country's rail transport network, also the longest in the world at 182,412.3 mi (293,564.2 km), handles mostly freight.

Privately owned railroads and trains were the dominant mode of transportation in the U.S. until the mid-twentieth century. The introduction of jet airplanes and airports serving the same major city routes accelerated a decline in demand for intercity rail passenger service by the 1960s. The completion of the Interstate Highway System also hastened the sharp curtailment of passenger service by the railroads. These significant developments led to the creation of the National Railroad Passenger Corporation, now called Amtrak, by the U.S. federal government in 1971. Amtrak helps to maintain limited intercity rail passenger service in most parts of the country. It serves most major U.S. cities, but outside the Northeast, California, and Illinois it typically runs only a few trains per day. More frequent Amtrak service is available in regional corridors between certain major cities, particularly the Northeast Corridor between Washington, D.C., Philadelphia, New York City and Boston; between New York City and Albany; in metropolitan Chicago; and in parts of California and the Pacific Northwest. Amtrak does not serve several major U.S. destinations, including Las Vegas and Phoenix, Arizona.

The Oldsmobile Curved Dash and the Ford Model T, both American cars, are considered the first mass-produced and mass-affordable cars, respectively. As of 2023, the United States is the second-largest manufacturer of motor vehicles and is home to Tesla, the world's most valuable car company. American automotive company General Motors held the title of the world's best-selling automaker from 1931 to 2008. The American automotive industry is the world's second-largest automobile market by sales, having been overtaken by China in 2010, and the U.S. has the highest vehicle ownership per capita in the world, with 910 vehicles per 1000 people. By value, the U.S. was the world's largest importer and third-largest exporter of cars in 2022.

The American civil airline industry is entirely privately owned and has been largely deregulated since 1978, while most major airports are publicly owned. The three largest airlines in the world by passengers carried are U.S.-based; American Airlines is number one after its 2013 acquisition by US Airways. Of the world's 50 busiest passenger airports, 16 are in the United States, including the top five and the busiest, Hartsfield–Jackson Atlanta International Airport. As of 2022, there are 19,969 airports in the U.S., of which 5,193 are designated as "public use", including for general aviation and other activities.
Le transport ferroviaire de voyageurs

Les services longue distance et de banlieue d'Amtrak ont leur origine à la gare Union. Chicago est l'un des plus grands nœuds du réseau ferroviaire de voyageurs du pays. Les services se terminent dans la région de San Francisco, à Washington, D.C., à New York, à La Nouvelle-Orléans, à Portland, à Seattle, à Milwaukee, à Quincy, à St. Louis, à Carbondale, à Boston, à Grand Rapids, à Port Huron, à Pontiac, à Los Angeles et à San Antonio. Les services futurs se termineront à Rockford et Moline. Une tentative a été faite au début du 20e siècle pour relier Chicago à New York via la Chicago – New York Electric Air Line Railroad. Des parties de cette ligne ont été construites, mais elle n'a jamais été achevée.
### Query ###
Je vois que les États-Unis ont un système ferroviaire très développé avec plus de 180 000 miles de voies, mais que Amtrak ne dessert pas certaines grandes villes comme Las Vegas et Phoenix. Est-ce que quelqu'un peut m'expliquer pourquoi ils ne desservent pas ces destinations majeures ?

### Main Text ###
Transportation

The overwhelming majority of roads in the United States are owned and maintained by state and local governments. Roads maintained only by the U.S. federal government are generally found on federal lands (such as national parks) or at federal facilities (like military bases). The Interstate Highway System, with its large, open freeways linking the states, is partly funded by the federal government but owned and maintained by the state government hosting its section of the interstate. Some states fund and build their own large expressways — often called " parkways " or " turnpikes " — that generally use tolls to pay for construction and maintenance. Likewise, some privately owned roads may use tolls for this purpose.

Passenger and freight rail systems, bus systems, water ferries, and dams may be under either public or private ownership and operation. U.S. civilian airlines are all privately owned. Most U.S. airports are owned and operated by local government authorities, and there are also some private airports. The Transportation Security Administration has provided security at most major airports since 2001.

The U.S. Department of Transportation and its divisions provide regulation, supervision, and funding for all aspects of transportation except for customs, immigration, and security. (The latter remain the responsibility of the U.S. Department of Homeland Security.) Each U.S. state has its own department of transportation, which builds and maintains state highways. Depending upon the state, this department might also directly operate or supervise other modes of transportation.

Aviation law is almost entirely the jurisdiction of the U.S. federal government. Vehicle traffic laws, however, are enacted and enforced by state and local authorities, with the exception of roads located on federal property (national parks, military bases) or in the unorganized U.S. territories. The United States Coast Guard is the primary enforcer of law and security on U.S. waterways, inland as well as coastal, but economic jurisdiction over coastal tidelands is shared between state and federal governments. The country's inland waterways are the world's fifth-longest, totaling 41,009 km (25,482 mi).

Of the world's 50 busiest container ports, four are located in the United States. The busiest in the U.S. is the Port of Los Angeles.

Personal transportation in the United States is dominated by automobiles, which operate on a network of 4 million miles (6.4 million kilometers) of public roads, making it the longest in the world. The country's rail transport network, also the longest in the world at 182,412.3 mi (293,564.2 km), handles mostly freight.

Privately owned railroads and trains were the dominant mode of transportation in the U.S. until the mid-twentieth century. The introduction of jet airplanes and airports serving the same major city routes accelerated a decline in demand for intercity rail passenger service by the 1960s. The completion of the Interstate Highway System also hastened the sharp curtailment of passenger service by the railroads. These significant developments led to the creation of the National Railroad Passenger Corporation, now called Amtrak, by the U.S. federal government in 1971. Amtrak helps to maintain limited intercity rail passenger service in most parts of the country. It serves most major U.S. cities, but outside the Northeast, California, and Illinois it typically runs only a few trains per day. More frequent Amtrak service is available in regional corridors between certain major cities, particularly the Northeast Corridor between Washington, D.C., Philadelphia, New York City and Boston; between New York City and Albany; in metropolitan Chicago; and in parts of California and the Pacific Northwest. Amtrak does not serve several major U.S. destinations, including Las Vegas and Phoenix, Arizona.

The Oldsmobile Curved Dash and the Ford Model T, both American cars, are considered the first mass-produced and mass-affordable cars, respectively. As of 2023, the United States is the second-largest manufacturer of motor vehicles and is home to Tesla, the world's most valuable car company. American automotive company General Motors held the title of the world's best-selling automaker from 1931 to 2008. The American automotive industry is the world's second-largest automobile market by sales, having been overtaken by China in 2010, and the U.S. has the highest vehicle ownership per capita in the world, with 910 vehicles per 1000 people. By value, the U.S. was the world's largest importer and third-largest exporter of cars in 2022.

The American civil airline industry is entirely privately owned and has been largely deregulated since 1978, while most major airports are publicly owned. The three largest airlines in the world by passengers carried are U.S.-based; American Airlines is number one after its 2013 acquisition by US Airways. Of the world's 50 busiest passenger airports, 16 are in the United States, including the top five and the busiest, Hartsfield–Jackson Atlanta International Airport. As of 2022, there are 19,969 airports in the U.S., of which 5,193 are designated as "public use", including for general aviation and other activities.

### Supplementary Text ###
Le transport ferroviaire de voyageurs

Les services longue distance et de banlieue d'Amtrak ont leur origine à la gare Union. Chicago est l'un des plus grands nœuds du réseau ferroviaire de voyageurs du pays. Les services se terminent dans la région de San Francisco, à Washington, D.C., à New York, à La Nouvelle-Orléans, à Portland, à Seattle, à Milwaukee, à Quincy, à St. Louis, à Carbondale, à Boston, à Grand Rapids, à Port Huron, à Pontiac, à Los Angeles et à San Antonio. Les services futurs se termineront à Rockford et Moline. Une tentative a été faite au début du 20e siècle pour relier Chicago à New York via la Chicago – New York Electric Air Line Railroad. Des parties de cette ligne ont été construites, mais elle n'a jamais été achevée.

### Draft ###

Query breakdown: "180,000 miles voies" + "Las Vegas/Phoenix pas desservies" → why major omissions?

First verify numbers. ● 182,412 miles confirmed (Amtrak data 2020). ● Two largest US cities without service - factually correct.

→ Need causal explanation, not just descriptive.

**Historical context crucial:**

Pre-1971: Private railroads dominated. Competition fierce.
1960s inflection point: 
- Highway expansion (Interstate System completion)
- Airline deregulation emergence
- → Passenger rail decline
- Economic model unsustainable

**Amtrak creation 1971:** Federal takeover to preserve skeleton network.
※ Key constraint: Limited federal funding → had to prioritize routes.

**Route selection logic:** ● High population density corridors ● Existing infrastructure ● Economic viability

Northeast Corridor: Boston-DC-NYC triangle = maximum ridership density
California: Population centers + tourism demand  
Illinois: Chicago hub + state funding commitment

⟨H≈0.8⟩ But Vegas? Desert isolation, gambling destination - leisure travel patterns different. Phoenix expanding rapidly post-1970s, suburban sprawl, air competition. Southwest Airlines expansion 1970s-80s made short-haul air cheaper than rail...

**Physical/economic constraints:**
- Desert geography → expensive track maintenance
- Low population density → revenue challenges  
- Existing air infrastructure → redundant service
- Tourism patterns → peak demand unpredictable

**Comparison verification:**
France: High-speed TGV covers entire country (state subsidy model)
Germany: Extensive ICE network (federal funding)
US: Private profit model → federal bailout → selective service

∴ **Core answer:** Amtrak serves "economic corridors" not "geographic coverage." Las Vegas/Phoenix fell outside profitable route matrix despite population size.

**Final synthesis:** Historical decline + federal funding constraints + route economics + infrastructure legacy = selective service pattern.

! Key insight: "Major cities" ≠ "profitable train routes" in American context.

### Answer###
Votre observation est tout à fait correcte : Amtrak ne dessert effectivement pas Las Vegas et Phoenix, malgré le vaste réseau ferroviaire américain de 182 412,3 miles de voies.

Cette situation s'explique principalement par l'histoire du transport ferroviaire américain. Avant le milieu du 20e siècle, les chemins de fer privés étaient le mode de transport dominant dans le pays. Cependant, l'introduction des avions à réaction et l'expansion du réseau autoroutier Interstate ont accéléré le déclin de la demande de services ferroviaires interurbains de passagers dès les années 1960.

Face à ce déclin, le gouvernement fédéral américain a créé Amtrak en 1971 pour maintenir les services ferroviaires de passagers dans tout le pays. Amtrak dessert la grande majorité des grandes villes américaines, mais en dehors du corridor Nord-Est, de la Californie et de l'Illinois, la compagnie ne propose généralement que quelques trains par jour.

Les services ferroviaires à Amtrak sont concentrés dans les corridors régionaux à forte densité de population, notamment le corridor Nord-Est entre Washington D.C., Philadelphie, New York et Boston, ainsi que dans le sud de la Californie et le nord-ouest du Pacifique. Ces régions offrent un trafic de passagers suffisamment important pour rendre les services ferroviaires économiquement viables.

Les villes que vous mentionnez se situent en dehors de ces corridors à fort trafic où Amtrak a priorisé ses services.