From Sahih Bukhari (Hadith 1530):
Narrated Ibn `Abbas:The Prophet (ﷺ) fixed Dhul-Hulaifa as the Miqat for the people of Medina, Al-Juhfa for the people of Sham, Qarn-al-Manazil for the people of Najd, and Yalamlam for the people of Yemen; and these Mawaqit are for those living at those very places, and besides them for those whom come through them with the intention of performing Hajj and Umra; and whoever is living within these Mawaqit should assume Ihram from where he starts, and the people of Mecca can assume Ihram from Mecca
Reference: Bukhari 1530