Amtrak trains go straight into Washington DC. People take the train down for events in this area all the time.
Alternatively, you can grab the Bolt Bus, or others like it (https://www.boltbus.com/default.aspx). Cheaper and slower than Amtrak but apparently has decently usable wifi.
I'd ve loved it if it were also in India. Bangalore.
I second that.
Its far more difficult to organize in a different country. I was surprised to see it being held in London.