Answer:
The place where he spoke, the Lincoln Memorial in Washington DC, was quite significant to the message he was giving. DC is the capital of the U.S., which could've made it more of a well-known speech. DC is significant in the way of being home to a plethora of U.S. presidents makes the message of race that more loud. Additionally, it's a powerful move to have a speech about race in a country that was/kind of is racially rampant, and in terms of segregation, so powerful that a black man could stand at a prominent place in a large, known country in that point of time.