In the aftermath of a Bangladesh factory collapse that killed more than 600 people last month, a lot of people are asking where their clothing originated.

Why is it so hard to trace a T-shirt's origins?

A tank-top made in Bangladesh is displayed in an H&M store in Atlanta. (David Goldman/AP)That shirt you're wearing: where was it made? If you're not sure, you're not alone.But in the aftermath of a Bangladesh factory collapse that killed more than 600 people last month, a lot of people are asking where their clothing originated."Made in" garment tags may signal the country of manufacture, but the cotton-to-shelf story behind any given article of clothing is far more complex; So much ...