by R. Ari Enkin
While all the other Patriarchs and Matriarchs of the Jewish people were buried in Chevron, Rachel Imenu was an exception. God pre-determined that Rachel was to be buried along the side of the road on the way to Bethlehem in order for her tomb to serve as a place for prayer when the Jewish people would one day be led into exile by King Nevuzradan. When Rachel would hear the beseeching prayers of her children at upon her grave she would cry and plead on their behalf to God.
Although the date traditionally observed as the yartzeit for Rachel Imenu is the eleventh of Cheshvan, the accuracy of this date is far from unanimous within historical texts. The source for observing the eleventh of Cheshvan as the yartzeit is a Midrash which lists the dates that each of the founding fathers of the 12 tribes were to have been born on. It states there that Benjamin was born on the eleventh of Cheshvan. As the Torah records that Rachel died as she gave birth to Benjamin, we can derive from here that this day would be her yartzeit as well.
Nevertheless it appears from no less an authority than Rashi that Rachel's passing took place at the start of the summer, a view which is supported by others as well. Yet other sources contend that Rachel actually died between Pesach and Shavuot.
Along with so many other issues in Judaism, there are often a multitude of opinions and traditions, and this is no exception. Even the yartzeit of Moshe Rabbeinu, traditionally observed on the 7th of Adar is disputed with eminent authorities insisting that his yartzeit is to be observed on the 7th of Shevat. Nonetheless, there exists a concept within Torah thought that it is a Divine sign of legitimacy when ambiguous matters have been mainstreamed by the entire nation.
Some commentators suggest an additional reason as to why Rachel was buried in a separate location away from the other Patriarchs and Matriarchs. While prayer at Ma'arat Hamachpela is certainly meritorious and worthy of Divine favor, some suggest that prayer at the tomb of Rachel is even more powerful. Indeed, it is only Rachel who in addition to her righteousness also has the tremendous merit of having saved her sister from embarrassment. It is owing to her concern about her sister's dignity over her own that God specifically shows Divine mercy to those who pray there. Had she been buried along with everyone else we may not have been able to access her unique potential.
Be sure to make every effort to pray at Rachel's Tomb along with everyone else – on the eleventh of Cheshvan, the date Klal Yisrael has chosen to observe her yartzeit.
 Bereishit 48:7
 Yalkut Shemoni, Parashat Shemot; Rabbeinu Bechaya, Parashat Shemot
 Bereishit 35:16
 Siftei Chachamim, ad. loc.
 Pesikta 3 s.v. Bayom Hashmini
 Cited in Meoros Natan on Hilchot Chanukah by Rabbi Yitzchak Natan Kupershtok, in the introduction.
 Magen Avraham O.C. 580:8 in the name of the Yalkut Shimoni. Further study is required to understand why the Yalkut is relied upon as the date observed for Rachel's yartzeit, yet its registration of the yartzeit for Moshe Rabbeinu has been rejected.
 See for example Aruch Hashulchan O.C. 345:18 for a similar idea.
 A "must read" Midrash about Rachel's merits is to be found in Eicha Rabba, in the introduction.