In an Ancient Near East class at YU, Professor Kedar was "stuck" with a "Tzarich Iyyun" - namely "How could 2.5 million people leave Egypt w/o leaving a great roshem behind?"
Nearly every other phenomenon of the Exodus and sojourn to EY had been explained in detail, much with archaeological support
Later on at the Seder, I realized how Hazal probably addressed this very same issue
"V'es halachatz - zo had'chak". It seems like the Haggadah and Midrash Sifrei are not adding much to our understanding?!
Now in another class on Ethnic History of the USA, we learned how tenement life in the Lower East Side was oppressive; and that nearly 2 million people were crowded into a small area, one NYC neighborhood.
Now we can explain many things. One of the oppressions in Egypt was D'chak, that the Israelites were jammed into a tiny neighborhood. This not only provides us the explanation of the cruelty of the Mitzrim, but it also explains the logistics of how Israelites could be gathered from the four corners of Mitzrayim relatively quickly. It also explains how the Lachatz was not about work or other mistreatment, but was addressing the very nature of oppression via overcrowding.
Hag Kasher v'Samei'ach!