I can believe it might rank highest by other touring providers (higher than average incomes, pretty accessible logistics, hotels, parking relative to places like NY, LA, SF) or from hobbyists here who are looking for variety.  Sure there are some good providers and agencies here but not at the level of places like NY, Miami, LA.  I can say that when a new provider arrives or is touring I often find it difficult to book as the demand must be very high.  

Do you have any specific questions - don't hesitate to ask! Many ladies are based around DC and many more tour here. Tyson's Corner seems to be THE place to host - it's close to DC, hotels are cheaper and plentiful and generally parking at hotels is free.

I know some touring ladies no longer come into DC itself due to perceived crime and safety problems.

I checked out your website...we'd love to have you out here.