[sneakypete]

Why are bank robberies Federal crimes, if they don't cross State borders?

The justification for this is because the feds insure all individual depositer losses up to 100 grand,so that makes stealing money from a bank a federal offense. The reason this happened was the depression and bank robbers caused people to lose faith in banks in the 30's.

[drjimmy]

The justification for this is because the feds insure all individual depositer losses up to 100 grand,so that makes stealing money from a bank a federal offense.
Bingo! When you hear or see "FDIC" or "FSLIC" with a bank commercial, that means your deposits are insured by the federal government. And that means that the FBI investigates robberies from those banks (not all banks are federally insured).