What Is Meant by Jam-Packed?

to fill or pack as tightly or fully as possible: We jam-packed the basket with all kinds of fruit.

What does jam packed mean in slang?

adjective [oft ADJ with n] If somewhere is jam-packed, it is so full of people or things that there is no room for any more. [informal]

Why is it called Jam Packed?

In moderate to rapid informal speech, to avoid the “reset” necessary to pronounce the following p, the d following the collocation jammed packed would likely be elided, as in red and purple. The result would be jam packed, which may ultimately be the independent source for both Crocket and the American usage.