The University of Iowa sponsors nearly 400 exchange visitor scholars annually, who come to The University for research, teaching, observation, and other professional activities. International Student and Scholar Services (ISSS) provides immigration advising and orientation to visiting scholars. The following information will assist you before you arrive in Iowa City.
With the exception of citizens of Canada and Bermuda, all other potential exchange visitors must obtain a J-1 visa through a US consulate. As specific requirements and procedures do vary from consulate to consulate, you should inquire for any special needs at the location where you will be applying for a visa.
A listing of all US consulates, along with links to their web pages, is available at the Department of State  website. You must have a J‑1 visa to enter the United States for your J-1 activity. If you have another US visa (such as for a visitor) you cannot use that to come in as a J-1, and should you attempt to do so, you may be refused entry at the border or be unable to undertake the activities which you plan to do as a J-1.
Generally, you will need to make an appointment to apply for your J-1 visa, and the embassy web site can give you information on how to make the appointment. You will also need to pay a visa application fee (information again available on the embassy website) and a SEVIS fee  before your visa application can be submitted. Be sure to pay these fees in time to receive the appropriate receipts because if you do not have proof that you have paid both the visa application and SEVIS fees, you will not be able to apply for the visa. If you have dependents that will be applying for J-2 visas, you will need to pay a visa application fee for each, but not an additional SEVIS fee.
When you go to the consulate to apply for the J-1 visa, be sure to have a valid passport, the original DS-2019 form, receipts that show you have paid the appropriate fees, and proof of any non-University of Iowa funding that will be used to cover your stay in the United States. If you have dependents applying for J-2 status, you will also need to provide proof of their relationship to you (for example, a marriage license or birth certificate).
Please be aware that the University of Iowa cannot guarantee visa issuance, and cannot influence a consul if a visa is denied. Should you be denied a visa, you should ask for a written explanation of why you were denied, and then International Student and Scholar Services can advise you on how you might overcome the reason for denial. However, the final decision on visa issuance is made at the consulate, and the University cannot appeal the decision.
Citizens of Canada and Bermuda do not need to apply for visas, but must pay the SEVIS fee and have a receipt for that fee prior to applying for entry into the United States as a J-1 exchange visitor.