why?
Because they will not accept paper applications in the USA.
See here for how to apply in the US:
http://www.ukba.homeoffice.gov.uk/countries/usa/applying/?langname=UK%20English.
You can look at the paper form for reference (the VAF4a), but if you are applying in the US, you must apply online - it's the only way to do it, and it's the only way you can pay for the application and book your biometrics appointment.
The process is:
- Collect all your supporting documents, making sure everything is original, and make photocopies of everything
- Fill out the online application (this can be saved as you go)
- Submit the online application... when you submit it, you will be prompted to pay and to book a biometrics appointment
- Print out your completed application and biometrics appointment confirmation
- Print out Appendix 2 and fill it in (the financial and accommodation details for the application
- Attend the biometrics appointment, taking with you your passport and the printed appointment confirmation letter (they will stamp the letter and give it back to you)
- Put the stamped appointment letter with your printed application form and Appendix 2, and all your supporting documents and mail them to the UK consulate in NYC (if you want to purchase priority processing for $300 you can do this on the Worldbridge website just before you mail it)
- Wait for the visa to be processed