To travel to America, you will have to obtain a US visa and you cannot enter into America legally without a valid visa. But this visa alone may not permit you to get into the United States and with that visa, you can only travel to a US port of entry. At the border, an immigration officer will review your documents and determine whether you are eligible to enter into the country. In case, you are found to be inadmissible into America, you will not be permitted to get into the United States and you will be sent back to your home country. However, if you are not admissible into the country, you may apply for a waiver by filing Form I-601A, Application for Waiver of Grounds of Inadmissibility and if this petition is approved, you may be declared admissible into America and granted entry into the country.
Grounds of Inadmissibility
There are many reasons why a foreign national may not be permitted to get into the United States and you may be considered inadmissible into America if you fall into one of the following categories.
Health related issues
If you have a communicable disease and if you fail to provide the required vaccination records at the US port of entry, you will not be granted permission to enter into America. In this case, you will be considered inadmissible based on health related grounds. If you have a communicable disease such as, leprosy, tuberculosis or gonorrhea and if you do not present the required vaccination documents, you will be placed in detention and sent back to your country of citizenship. However, you may be granted a waiver, if you provide a medical certificate from a doctor saying that you cannot get vaccinated.
National Security
Terrorists, foreign nationals who are affiliated with criminal organizations and people who are suspected of engaging in undercover work are inadmissible. Likewise, foreign nationals who have provided financial assistance to groups that are against the government, cannot enter into America, even if they hold valid visas.
Criminal records
Criminals will never be granted entry into America and if you have been convicted of several crimes, you will be considered inadmissible into America. Money launderers, human or drug traffickers and former Nazis are also inadmissible.
Undocumented immigrants
People who have violated the immigration laws of the country cannot get into the country and people who have lived in America for three months or more, illegally, will not be granted entry into America. However, such immigrants may apply for waivers and they may be granted waivers if they prove that their removal from the country would result in hardship to their relatives in America.
Public Charge
You must be capable of financially supporting yourself. If not, you may not be granted entry into the country as the immigrants who are likely to become public charges are inadmissible into the country. Hence, you will have to prove that you will not become a public charge.