The Sibling of US Citizen category enables US citizens to sponsor their sister, brother, half-sister, half-brother, stepsister, stepbrother or adopted brother or sister living abroad or already residing in the United States to live and work in the US on a permanent basis.
If applying while the foreign sibling is in the US, the foreign sibling must have entered the US legally and continue to maintain lawful status. If applying while the foreign sibling is outside the United States, the foreign sibling must remain outside the US until the visa is granted.