If you are a US citizen, you can apply for immigration in regards to your parents, spouse, children (whether married or not), and siblings. If you are a US permanent resident (green card holder), you can apply for immigration for your spouse and unmarried children. Additionally, adoptive children, stepchildren, and spouses of deceased US citizens may apply for relative immigration under certain conditions.U.S. citizens can apply for immigration for their parents, spouse, children (whether married or not), and siblings. Among them, if a citizen applies for immigration for a parent, spouse, or unmarried child under the age of 21, the immigrant application beneficiary does not need to wait for the appointment. In addition, US citizens can apply for a K visa for a fiancé/wife who is abroad and apply for family immigration after getting married in the United States.