El trámite consular es cuando el beneficiario de una petición de inmigración, por ejemplo, un familiar extranjero a quien usted patrocina para que venga a los Estados Unidos, solicita una visa de inmigrante estadounidense en un consulado o embajada de los Estados Unidos en el país donde reside.
A person who wishes to immigrate to the United States essentially has two ways to obtain a green card:

The first step in the consular process is for the applicant to file for a visa with U.S. Citizenship and Immigration Services (USCIS) and then wait for it to be approved. For immediate relative petitions, an I-130 is filed. The I-130 approval process has different processing times depending on the type of family relationship. For the spouse of a U.S. citizen, the processing times for the I-130 can take 6 to 13 months, depending on several factors, including the workload that the USCIS is experiencing at the time the petition is filed.
Once the USCIS has approved the I-130, the case will be sent to the National Visa Center (NVC) where the case will be pre-processed.
At this time, the applicant will be required to submit a number of supporting documents to the NVC, including:
Once the National Visa Center has completed the pre-processing and a visa interview is available, the case will be transferred to the U.S. consulate or embassy abroad. It will be reviewed and an interview will be scheduled. This process can take another 90 days or more. Most recently, the waiting time has significantly increased and many people have been waiting well over a year for their interview abroad.