AWS Custom EC2 Images AMI (Amazon Machine Image) Have Regional Scope
Amazon Web Services has provided the ability to create custom AMI that allow you do many things like add a webserver and scripting languages and bake these products into your own custom AMI for later usage – see Amazon docs for details.
One key fact about those custom images is that the scope is regional. If you want to use the same custom AMI in multiple regions you have to copy it around.
BTW – Great care should be taken to address security concerns BEFORE you make a custom AMI public (default is private). Read the following before you even think about it: