A U.S. Citizen may sponsor a sibling in the Family-based Fourth Preference category, but as you recognize there is a very long waiting list for a visa to become available in order to adjust status. The U.S. Department of State's Visa Bulletin shows that visas currently are available for such cases (for people from most countries) with a Priority Date of January, 2000 or earlier. Since less than a year's backlog can be expected to be handled in a year, the wait may be 15-20 years.
While you may be able to file a form I-130 petition now, your sister would not be entitled to remain in the U.S. until a visa becomes available for her to apply to adjust status. If she is an adult and remains in the U.S. beyond the expiration of her original nonimmigrant visa, she may become subject to a 3-year or 10-year bar to re-entering the U.S. For these reasons, Family-based Fourth Preference rarely is a satisfactory immigration strategy, and it would be wise to consult with an immigration attorney to see whether other immigration eligibilities may exist.
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David N. Soloway
Frazier, Soloway & Poorak, P.C.
1800 Century Place, Suite 100
Atlanta, Georgia 30345 www.fspklaw.com
404-320-7000 * 1-877-232-5352 * firstname.lastname@example.org
If your sister is not a US citizen, she could not file an I-130 for you. If she is a US citizen, it would still take more than 10 years before you could apply for a green card based on your sister's petition. You would have to do consular processing, but if you leave after spending more than a year in the US without legal status, you will then have to wait outside the US another 10 years!
It may be possible for you to adjust status (obtain a green card without leaving the US), but only if your US citizen spouse, parent or adult child files a petition for you. The laws regarding "unlawful presence" and the resulting 3-year and 10-year "bars" are complicated and harsh, so you will need to understand them clearly, in order to make the best choice as to what path will be the best one.