Limit Nbr of items in asp:DropDownList?

[Guest]

How can I limit the number of items that show up in a dropdown list at one
time? I have a list of states, and because my dropdown list is near the
bottom of the page, it becomes a drop-up list. It would look a lot more
professional if it only had 20 items at a time, and dropped down normally. I
can't find a way to do this. Can anyone help?

Here's my dropdown list code:
<aspropDownList ID="ddState" Runat="Server"></aspropDownList>

and then it's data-bound in the code-behind.

Any help is appreciated! Thanks!