The application that I am currently working on required the use of a scrollable multiselect dropdown that contained checkboxes. We are using Angular.js on this particular project and after doing some research, I was able to find an example that was close to what I needed but needed slight modifications.
Update: A co-worker showed me dotansimha’s AngularJs Dropdown Multiselect Directive, which you can find here.
jaredwilli for the providing a starting template for me to modify.
mshafrir for providing the states list in json.
cskelly for the scrollable css style.