미국은 연방체제의 대표적인 국가로서 헌법에 의해 연방정부와 주정부가 실질적 통치권을 부여받음으로써 국가권력을 분점하고 있다. 주정부는 연방정부의 산하조직이 아니며 완전히 독립된 정부로서 헌법에서 정하는 예외를 제외하고 동등한 위치에 있다. 또한, 미국은 권력의 분립에 따른 상호견제를 기본으로 효율적으로 운영되고 있는 국가라 할 수 있다. 권력분립은 국가권력을 입법· 행정· 사법으로 나누어 각각의 권력을 독립기관에 담당시켜 기관 상호간에 억제와 균형관계를 설정하고 있다.삼권분립제도에서 의회는 법률의 제정권을, 대통령은 법률집행권을, 법원은 법률해석권을 갖는데, 상호견제장치는 어느 부도 절대적 권력을 행사하지 못하도록 하는 것이다. 상원의원과 하원의원, 대통령, 연방판사는 각기 다른 방법에 의해 선출된다. 그러나 시대상황이 변화하면서, 기관간의 기능중복 현상이 나타나기 시작하였다. 예를 들어, 의회의 입법권 위임금지는 독립규제위원회나 정부기관의 규칙 제정권으로 완화되었다. 그리고 다수의 입법안이 행정부에 의해 입안된다거나 연방대법원에 의한 위헌판결은 결과적으로 사법부가 법률제정 기능까지 담당하게 되는 등 기관간의 권력중복현상이 빈번하게 이루어지고 있다.연방정부는 전통적으로 대통령실(Executive Office of the President), 행정부처(Departments), 독립기관 및 공사(Independent Establishments and Government Corporations)로 구분되고 있다.대통령실은 백악관사무국과 부통령실을 중심으로 경제자문회의, 환경위원회, 국가안전보장회의, 행정관리실, 관리예산처, 국립마약통제정책실, 정책개발실, 과학기술정책실, 미무역대표부가 존재하고 있다. 이 밖에 U.S. Government Manual에 나타나지 않는 실이나 위원회도 있는데 다음과 같다. 국립에이즈정책실(Office of National AIDS Policy), 대외홍보실(Office of Global Communications), 신뢰기반· 공동체정책실(Office of Faith-Based and Community Initiatives), 백악관군사실(White House Military Office), 대통령대외정보자문위원회(President`s Foreign Intelligence Advisory Board)이다.미국의 행정부처는 농가소득 향상과 농산물 판매를 위한 해외시장개척을 위한 농무부, 국제시장에서 미국의 경쟁력을 강화하는 상무부, 군사력제공 및 적으로부터 미국보호를 담당하는 국방부, 국민들의 평등한 교육권을 보장하고 국가전체의 교육상의 탁월함을 진작하는 교육부, 에너지 관련기능의 조정과 집행을 담당하는 에너지부, 공공보건사업 추진 및 알콜· 마약· 정신병관리 그리고 질병통제와 식품· 약품관리를 담당하는 보건후생부, 주택건설사업 및 주거기회제공을 담당하는 주택도시개발부, 국가의 천연자원과 문화유적의 보호 등을 담당하는 내무부, 법집행 및 범죄예방 업무 등을 담당하는 법무부, 임금노동자의 복지 증진 및 근로조건 개선, 고용기회의 증진 등을 목표로 하는 노동부, 대외정책의 수립과 집행에 있어서 대통령에게 조언하고 대외관계에서 미국의 안전과 복지증진을 추구하는 국무부, 국가의 모든 교통정책 수립 및 관리를 담당하는 교통부, 경제· 재정· 조세· 예산정책을 수립하고 재정담당기관으로서의 업무를 수행하는 재무부, 재향군인 및 그 가족에 대한 각종 지원프로그램을 운영하는 재향군인부의 14개 부처에 국토안보부가 추가되었다. 국토안보부는 2001년 9· 11테러를 계기로 신설되었으며 미국의 국가안위에 관한 기능을 수행하고 있다.미국의 독립기관 및 공사는 국가의 전반적인 분야에 있어서 국가안보에 관한 중요한 정보를 수집· 평가· 전달하는 것은 기본목적으로 하는 중앙정보국, 미국의 상품이나 서비스의 수출에 대한 재정지원을 통해 미국의 산업을 유지하고 창출하여 사적 부문을 지원하는 미수출입은행, 미국의 중앙은행의 역할을 하는 연방준비제도 이사회, 실적제도의 완결성을 보호하고 공무원의 권리를 보장하는 실적주의제도보호위원회, 연방정부공무원의 인사와 실적제도 및 인적 자원관리를 담당하는 인사관리처 등 55개의 독립기관 및 공사로 조직되어 있다.

The United States is a representative country of the Federal System. As Federal and State governments are substantially granted sovereign power according to the constitutional law, National power is divided. As State government is not an affiliated organization of Federal government but the completely separated government,it is in the equal position excluding the exception provided by the law as well. In addition the United States is a country to be effectively operated based on mutual check by division of powers. Division of power divides national power into legislation, administration and judicature and let independent organization control each power so that it establishes the relationship of check and balance between each organization.In the separation system of Three Powers Congress has the legislation right, Presidenthas enforcement right of the law and the court has the construction right of the law and the mutual restraint system is that none of organization is able to exercise absolute power. Also a Senator, a Representative, the President and a Federal judge are elected by different ways. As the circumstance of times has been changed, the functional overlapping among organizations however has appeared. For example the prohibition of legislation mandate is eased into Independent Regulatory Commission or enactment right for regulation of governmental organization. Moreover, the power overlapping frequently occurred as many legislative bills are drawn up by Administration Department or judgmentfor violation of constitution by Federal Supreme Court which means Judicature department is in charge of enactment of the law in result.Federal Government is traditionally divided into Executive Office of the President, Departments and Independent Establishments and Government Corporations.Executive Office of the President includes Council of Economics Advisers, Council on Environmental Quality, National Security Council, Office of Administration, Office of Management and Budget, Office of National Drug Control Policy, Office of Policy Development, Office of Science and Technology Policy, Office of the United States Trade Representative centering around the White House Office and Office of the Vice President of the United States. Besides there are other departments and commissions which are not mentioned on U.S Government Manual and the lists areOffice of National AIDA Policy, Office of Global Communications, Office of Faith-Based and Community Initiatives, White House Military Office and President`s Foreign Intelligence Advisory Board. The Departments of the US include Department of Agriculture which is to improve an income of a farmhouse and to develop an international market for selling agricultural products, the Department of Commerce which is to enforce the competitiveness of the US in an international market, the Department of Defense which is to provide the Military power and to protect the US, the Department of Education which is to secure the national equal education right and to stimulate educational prominence in an entire country, the Department of Energy which is to adjust and execute Energy related functions, the Department of Health and Human Service which is to control the alcohol, a drug, a mental disease, a disease control, food and medicines, the Department of Housing and Urban Development which is to be in charge of provision of dwelling opportunity and a housing construction project, the Ministry of Home Affairs which is to protect natural resources and cultural remains of a country, the Department of Justice which is to enforce the law and to prevent a crime, the Department of Labor which is to promote welfare of a wage worker and to improve working condition, the Department of State which is to advise the President in regards to establishment and execution of international policy, the Department of Transportation which is to establish and to control all kinds of transportation policy of a country and the Department of the Treasury which is to establish economic, financial, taxation and budgetary policies and to perform affairs as the financial department in charge. Alsothe Department of Homeland Security is added to 14 departments of Department of Veterans Affairs which is to operate various supporting programs for veteran soldiers and their families. The Department of Homeland Security has been established due to 9.11 Terror of 2001 and is performing the functions related to National security.The independent organizations and the public corporations of the US include 55 of the independent organizations and the public corporations such as the Central Intelligence Agency which is to collect, to evaluate and to convey important information in regards to the national security in entire fields of a country, Export Import Bank of the US which to maintain, to stimulate the business in the US through financial support in regards to export for exports and services of the US and to support private field, the Federal Reserve System which is to take an important role as the central bank of the US, Merit System Protection Board which is to protect completion of the merit system and to secure the right of a government employee and Office of Personnel Management which is to be in charge of personnel and the merit system of the federal government employee and to control Human Resources Management.