美国总统奥巴马将在星期三(8月28日)华盛顿民权大游行50周年纪念日发表主题演说。1963年举行的那次历史性示威要求平等权利，吸引了25万人聚集在林肯纪念堂。

奥巴马是美国历史上第一位黑人总统，他将对参加纪念仪式的数以万计的人发表演说。

50年前的历史性事件以黑人牧师马丁·路德·金“我有一个梦”的著名演说达到高潮，他的演说以种族和谐和公正为主旨，被历史学家称之为最伟大的演讲之一。

传媒界名人奥普拉·温弗雷、前总统吉米·卡特和比尔·克林顿也将出席星期三的纪念仪式。

1963年“进军华盛顿争取就业与自由”大游行发生在美国民权运动的高潮期。这场运动要求确保所有人的权利都能得到法律的平等保护。民权运动号召废除种族隔离制度。把黑人和白人分隔的做法符合当时的法律，民权运动的这项诉求遭到社会上很多人的强烈有时甚至是暴力的抵制。

U.S. President Barack Obama will give the keynote address at Wednesday's observance of the 50th anniversary of the March on Washington, the historic 1963 demonstration for equal rights that drew more than 250,000 people to the Lincoln Memorial.

Mr. Obama, the nation's first black president, will deliver his remarks to tens of thousands of people who are expected to attend the commemoration.  

Also appearing at Wednesday's anniversary observance will be former presidents Jimmy Carter and Bill Clinton, and media personality Oprah Winfrey.  

The march 50 years ago was capped by the Reverend Martin Luther King, Junior's famous "I Have a Dream" speech for racial harmony and justice, hailed by historians as one of the greatest ever delivered.

The 1963 "March on Washington for Jobs and Freedom" was held at the height of the American civil-rights movement that was aimed at ensuring the rights of all people are equally protected by the law.  The movement had faced strong and sometimes violent resistance to ending the practice of segregation that treated white and black Americans differently under the law.