'Rashi' Divrei ha'Yamim II, 10:1, 15: This was from Shamayim to fulfill "Kero'a Ekra Es ha'Mamlachah [and I will give it to your servant]" (Melachim I, 11:11). Shechem was in Efrayim's portion, and Yaravam was from Efrayim. Also ¹ , "Lo Yasur Shevet mi'Yhudah? Ad Ki Yavo Shilo v'Lo Yikehas Amim" (Yehudah will rule over all 12 tribes until the Shevatim come to Shechem, which is near] Shilo ² ).

Radak: Shechem was in Efrayim. Achiyah ha'Shiloni's Nevu'ah about Yaravam became known, therefore Yisrael sent for him to come. They looked for an excuse to turn the kingship to him. Therefore, they did not want to come to Yerushalayim, rather, to Shechem, which is in Efrayim, and Rechav'am needed to come to Shechem.

Radak citing Sanhedrin 102a: Shechem was designated for punishment. Dinah was raped there, they sold Yosef there, and Malchus Beis David was divided there.

Malbim: Really, Rechav'am did not need to be anointed or declared king. We do not anoint a Melech ben Melech (Horiyos 11b) (unless there is a dispute). Yisrael sought a pretext and came to declare him king. Via this, they informed him that he is not king until they choose to declare him king, and he will fulfill the stipulations they will make for him. Therefore they came to Shechem and not to Yerushalayim, for there his Shevet Yehudah would strengthen him. Shechem was the head of Yosef and opposed Yehudah - "va'Yim'as b'Ohel Yosef? va'Yivchar b'David Avdo" (Tehilim 78:67, 70). This is why they chose Yaravam, from Efrayim, to be their leader.