Often when you file an immigration application to petition your relative to get a green card to live and work permanently in the USA, the biggest question is how long will the process take. Most immigrants want to plan their lives around getting a green card so that they can make arrangements in their home country to permanently move to America. It would be much easier to plan if the USCIS can issue exact dates of when you will be fingerprinted, interviewed and receive your green card in the mail. However, as many potential immigrants found out the hard way, there is actually no way to tell how fast or slow a green card petition will be approved and processed.
The green card process always begins with an I-130 Petition for a relative to get a green card. The US citizen relative will file this form to let the USCIS know that they would like to sponsor a relative to come live and work in America. When the relative is already in America, this is called Adjustment of Status. The reason being that the relative must already be inside the country on a different status, often a student visa or a tourist visa. This is always the fastest way to receive a green card because there is no need to send documents back and forth to overseas US embassies and everything can be processed right here in America. The most common are green card through marriage to US citizen and green card for parents of US citizens. The only downside with filing for a green card while in America is that you have to be careful about travelling out of the country during the application processing. If you follow the guides linked, and you also file for I-131 Advanced Parole, you can travel out of the country as soon as you receive your Employment Authorization Card with Advanced Parole approval endorsement. If you don’t file the I-131 with your green card application, and you travel out of the country before you receive your green card, your application will be considered abandoned and terminated. Filing an adjustment of status for immediate relatives of US citizens (parents, spouses, and children) takes typically 3-9 months to complete, assuming no complications with documents and request for further evidence.
If the relative is not inside the USA, then things get complicated and the time lines become uncertain. Even with very straight forward cases such as for spouses or parents of US citizens, because the process is completely different for relatives overseas, the time to get a green card is almost always considerably longer than adjustment of status. The reason is that when a US citizen files the I-130 petition and it is approved, the application package is then sent to the National Visa Center (NVC) where it is reviewed again and then processed through their system. Often during this phase, NVC will ask for more documents to be sent for review. Once it is complete at NVC, the NVC then sends the immigration application package to the local US embassy where the relative is residing. The green card application is now waiting for a local immigration officer at the US embassy to review and schedule the interviews with the relative. Depending on how busy or political instability of the country, the US embassy immigration officers may or may not work at the fastest speed. Your green card application could be sitting at the local US embassy for a while before it even gets looked at by someone. In the best case scenarios, typical immediate relative filings take about 1 to 1.5 year to complete. The worst case is what you can imagine, years and years without hearing anything from anyone.
In conclusion, nobody can tell definitively how long your green card application will take. There are ballpark estimates of time based on past applications and past experiences, but every case is unique. Every green card application has a chance to be processed quickly and efficiently and every application also has an equal chance to be stuck in the bureaucracy of USCIS and hang forever. However, the best way to optimize your green card application is to file it through Adjustment of Status with the relative already in America. This is always the fastest and gives you the best chance to have a fast and speedy application.