You might need a visa to travel to US, see:

In order to get an invitation letter for the visa application, please provide the following information of the participant:

  • full name and contact (email and address)
  • copy of registration receipt for ICRA 2015
  • copy of passport information page
  • name of the workshop

This information can be emailed to [email protected] and the conference organizers will generate a letter and send it back by email. Please write ICRA_CPG_WORKSHOP_VISA in the email subject field.