United States of America

The United States of America (アメリカ合衆国) is a country that takes up most of Northern American continent in the Earth's western hemisphere, and is bordered by Canada in the north and Mexico in the south.

Background
The country is a federal government with fifty states, Hawaii being the last state to join the union, with each state being being partially self-governing and is united by central (federal) government. The country's government is the representative of the people, and decisions made by the head of state and other officials must govern under its constitutional law, the head of state and other officials are chosen by election, making the country a constitutional republic. The country has three distinct branches of government: executive, legislative, and judiciary. These branches and their various powers are delineated in the U.S. Constitution; the powers are specified in greater detail in laws enacted by Congress.

The seat of government of the United States is in Washington, D.C., a geographical area that is not located within any state.

The current president of the United States of America in the current timeline is Roberto Katze, and is the third Hispanic president to be elected.

Dealings with the Science-side
Though America isn't a part of the Science-side, on its own it has been trying to develop esper powers on their own since the Cold War. Though, still behind Academy City in terms of technology, the United States is still one of the foremost powerful economic and military entities in the world. The United States is the only country currently known to have invested a notable effort in creating their own esper program, though with limited success.

Angel Fall Arc
Washington, D.C. is briefly seen in television, in the first season of the Toaru Majutsu no Index anime. Here, Shirai Kuroko's form is taken-up by the President of the United States of America, saying Barack Obama's famous line: Yes we can. Needless to say, Kamijou Touma, due to the effects of his Imagine Breaker making him unaffected by the spell, as well as being ignorant of the spell's affect, is completely shocked by discovery, leading him to believe that the recent switching of personalities and the inexplicable appearance of people he knows around him is not just a mere prank.

Tree Diagram Remnant Arc
The United States was one of the countries that launched spacecraft to retrieve the remains of the destroyed Tree Diagram.

World War III
The United States of America, allied with the United Kingdom of Great Britain and Northern Ireland, and part of the science-side, takes part in the War, but their contributions are largely overshadowed during the event, due to to Academy City's overwhelming technological superiority, as well as the appearance of a power they could not wholly understand, the magic.

Hawaii Invasion Arc
Due to the strange movements of several people, including high government officials, President Roberto Katze leaves the side of his protection to investigate the mysterious occurrences. He would later be involved in trying to stop an invasion of Hawaii, and later the turning of the United States into a theocracy by Olay Blueshake with the help of GREMLIN and Trident. With the aid of the Kamijou Faction and the Dawn-Colored Sunlight, Roberto and the United States military was able to stop the invasion, though at a great cost, the volcano, Kilauea still erupted, furthering GREMLIN's plans.

Magic God Othinus Arc
Still reeling from the attack in Hawaii and with GREMLIN becoming even more brazen with their actions, the United States of America becomes involved in the opposition against GREMLIN, seemingly leading the international coalition, the Anti-GREMLIN Alliance, formed from various nations to oppose GREMLIN.

Kamijou Touma notes that the United States of America sets itself apart from the other dogmatic powers of the science and magic side by being the most rational. Indeed, it is Roberto who is the first one of the international coalition's leaders to lay down his pride and trust humanity that they will not give into the fear of the power of a magic god like Othinus.

Trivia

 * In the Toaru Majutsu no Index universe, the United States of America is stereotyped as a nation obsessed with guns as depicted in Toaru Kagaku no Railgun SS: Liberal Arts City, and is often referred to as the world's largest gun country, even though there is some truth to it.