Select2 can take a regular select box like this:
Alaska Hawaii California Nevada Oregon Washington Arizona Colorado Idaho Montana Nebraska New Mexico North Dakota Utah Wyoming Alabama Arkansas Illinois Iowa Kansas Kentucky Louisiana Minnesota Mississippi Missouri Oklahoma South Dakota Texas Tennessee Wisconsin Connecticut Delaware Florida Georgia Indiana Maine Maryland Massachusetts Michigan New Hampshire New Jersey New York North Carolina Ohio Pennsylvania Rhode Island South Carolina Vermont Virginia West Virginia
And turn it into a customized select box:
This allows you to quickly add a search box that will allow you to filter the options.
Select2 also supports multi-value select boxes:
As long as the select box has the multiple attribute set, Select2 will automatically pick this up.
multiple