USA: Immigration, Customs and Borders

The US immigration system has been in place in some form for many years, with the objectives of keeping the US secure and also to protect the welfare of US citizens, for example making sure that they have job opportunities that are not impacted by foreign nationals.
When someone is planning a trip to the US, they are required to obtain the relevant visa that provides authorization for them to make their trip. The type of visa that they are eligible for depends on numerous factors, including which country they are a citizen of, plus the purpose of their trip.
An ESTA is one form of non-immigrant travel authorization that citizens visiting the US for tourism or business purposes for a short period can apply for as long as they are from a country that is part of the Visa Waiver Program. For visits that are for longer periods than 90 days, it is necessary to apply for a different type of visa.
Students, skilled workers, ship crew and certain other occupations all have specific visas that are available for longer visits to the US.

Immigration to the US

Where a person is wishing to immigrate to the US, they must qualify for an immigrant visa, which come in different types:
Employment visas - For an employment based visa the applicant will require sponsorship from a US employer and will need to have a petition Form I-140 approved by the USCIS. The employer must first have obtained certification from the US Department of Labor to confirm that the work could not be performed by US workers. The application process includes providing documentation that proves relevant qualifications or other proof if the employment is based on extraordinary ability in a certain field.
Family visas – Another immigrant visa category is a family visa, where you can qualify through a spouse, parent, child or sibling that is a US citizen. The relative will be your sponsor and they will file the immigrant visa Form I-130 petition on your behalf. These types of visas generally take a long time to process and are usually over six months processing time.
Fiancé/fiancéé visas - One more immigrant visa type is a Fiancé/Fiancéé visa where a petition can be filed by someone you are intended to marry, provided you are legally married within 90 days of entering the US. The form I-129F petition must be completed by your US citizen fiancée/fiancé to process your application.

Steps: Applying for immigration visas

For all of these visa types, there is a strict process for getting the visa approved which includes an interview and medical examination at the US Embassy. You will also be required to provide documents to support your application that will be requested when you submit your petition.
The number of visas that the US issues each year is limited for many visa categories, as a way to control the volumes of immigrants entering the US. For example, approximately 140,000 employment-based visas are made available for application under the US immigration law.
As the processing time can be very long for immigration visas, it is recommended that you do not buy flights or arrange accommodation until you have received your visa.

Dependents

Many of the US visas have derivative visas for the spouse and children of the visa holder so that they can live with them in the US. For example, E-2 and C-2 visas can be applied for by all family members.
Customs
Before travelling to the US, it is important to check the prohibited items as there are numerous foods that you are not allowed to take across the US border. When you arrive in the US, you will be inspected by the Customs and Border Protection officers who will check your visa.