大多数美国人对领导这个国家的总统都有一个大致的了解, perhaps not everyone of the 46 总统s, but the most famous or controversial. Our first 总统, George Washington, is recognized as the “Father of our Country”; Abraham Lincoln is remembered as the “Great Unifier” during the Civil War; Franklin Roosevelt led our country through the Great Depression and World War II; John F. 肯尼迪, as the youthful 总统 of a new generation, was assassinated in Dallas; and Barack Obama, our nation’s first African-American 总统, opened the doors for other leaders of color. These 总统s join other noteworthy Chief Executives like Thomas Jefferson, Teddy Roosevelt, Dwight Eisenhower, Lyndon Johnson, 罗纳德·里根和比尔·克林顿，他们创造了国家目标和希望, responding to pressing social and economic issues, 在发生国家紧急情况时保护国家，并制定对国家发展方向产生持久影响的公共政策.
但是，尽管许多总统因其对国家进步的贡献而得到认可, and some have been long forgotten or vilified for their misfortunes, the office of the 总统 of the United States, the Presidency, 往往缺乏对这46个人在入主白宫时所拥有的权力和责任的理解. If we as Americans are to gain a greater appreciation of our 总统s, their challenges, their accomplishments and their failures, 重要的是要研究这个职位和那些占据这个职位的人是如何在我们的宪法体系内运作的.
美国的治理体系通常被描述为权力分立-立法, executive and judicial. 但是，虽然立法部门在宪法中首先被提及，并被赋予了许多权力和责任, it is the executive branch, the 总统, 这已经成为我们政府的核心和我们国家的决定性领袖. 而公共政策倡议和立法往往是国会和总统之间相互作用和妥协的结果, it is the 总统 who sets the policy agenda, 然后利用他作为行政部门首脑的地位，在错综复杂的立法程序中推进这一议程, judicial decisions and partisan give and take. This process is best described as based on the principle of checks and balances. 美国公众和历史经常评判总统是否有能力兑现其政策承诺，并有效地通过错综复杂的立法制衡.
The powers of the 总统 are a mix of substantive actions and ceremonial duties. 以下是总统要求的基于宪法的活动清单，以及通常伴随这些活动的礼仪职责:
- Represent our nation in talks with foreign countries and leaders.
- Negotiate and sign treaties with foreign countries, only with Senate consent.
- 做一些象征性的动作，以树立民族自豪感和爱国主义精神.
- 签署国会通过的法案，否决总统不愿支持的法案.
- 作为首席执行官-执行和执行国会通过的法律.
- Act as Commander in Chief of the armed forces.
- 对应该成为法律的政策提出建议——通常在国情咨文中提出.
- Grant pardons for those convicted of a crime.
- Nominate Cabinet members, 联邦法院系统的法官和其他高级官员，并欢迎外国政府的大使级代表.
- 就国内和国际重要事务向全国和全世界发表讲话.
美国总统的每一项权力和责任都是重要的，对国家的正常运作至关重要, but not all are of equal weight in terms of the process of governing. 例如, 作为行政长官的总统有巨大的权力与庞大的官僚机构合作通过规则, 规定, instructions and orders which in many cases have binding force of law. And when legislation is passed through Congress and signed by the 总统, 执行阶段的特点是特殊性和复杂性，因为法律往往是泛泛的，缺乏确保遵守的明确程序. In recent years because of a divided Congress, 乔·拜登(Joe Biden)总统诉诸行政命令来实施无法在国会通过的政策. 通常是在总统和国会对行政命令有分歧的情况下, 联邦法院参与决定行政命令的合法性.
In the area of foreign policy, the 总统 has the power to negotiate treaties with foreign countries, but because Congress must be a partner in this process, the final treaty must require a two-thirds vote of approval by the Senate. In many cases, the two-thirds vote is a difficult hurdle to cross leaving treaties unsigned, rewritten or without proper implementation. But while foreign treaties face key obstacles, 总统作为总司令的角色允许他在没有国会特别批准的情况下做出更大的军事决定. Although declaring war is the constitutional responsibility of the Congress, 总统可以利用他作为总司令的角色命令军队进入特定的国家或地区以实现军事目标. United States intervention in Vietnam, the Dominican Republic, 格林纳达, 例如，科索沃和阿富汗就是总统利用他作为总司令的权力派遣军队进入战区的结果. Using the power of Commander in Chief to attain a military objective, 然而, does create tension with the Congress, 它保留了预算和支出的权力，经常批评总统缺乏适当的协商，并强行通过军队和武器的拨款. 不过, 总统的外交政策和军事权力是他控制的两个责任领域，这使他有相当大的权力来制定对外关系方面的政策.
因为我们的政府体制是权力分立和制衡的体制, 总统在回应两党制框架的要求和法院的宪法角色时，必须在政治上娴熟. 此外, 总统必须有能力以支持其立法议程的方式引导公众舆论. 开国元勋们有意将我国的治理体系复杂化，使之具有三权分立和众多限制过度权力的手段. Yet over the history of our country, 成功处理这些限制和要求的总统在应对国内危机方面取得了成功, strengthening our economy and protecting our nation from foreign threats.