Why was Philadelphia the capital of the US during the American Revolution?

Answer

It was the largest and most culturally important city in North America at the time. Around 1800 it was overtaken by New York in those areas, and ten years earlier it was decided to build a brand new capital outside the existing states, on a piece of land between Virginia and Maryland, the neutral ‘District of Columbia’ – the relocation of government and parliament only found resp. in 1799-1800 place.