<ul id="dropdown3">
   <li>
     <a href="#">AL East     </a>
     <ul>
       <li>
         <a href="#">Baltimore Orioles         </a>
       </li>
       <li>
         <a href="#">Boston Red Sox         </a>
       </li>
       <li>
         <a href="#">New York Yankees         </a>
       </li>
       <li>
         <a href="#">Tampa Bay Rays         </a>
       </li>
       <li>
         <a href="#">Toronto Blue Jays         </a>
       </li>     </ul>
   </li>
   <li>
     <a href="#">AL Central     </a>
     <ul>
       <li>
         <a href="#">Chicago White Sox         </a>
       </li>
       <li>
         <a href="#">Cleveland Indians         </a>
       </li>
       <li>
         <a href="#">Detroit Tigers         </a>
       </li>
       <li>
         <a href="#">Kansas City Royals         </a>
       </li>
       <li>
         <a href="#">Minnesota Twins         </a>
       </li>     </ul>
   </li>
   <li>
     <a href="#">AL West     </a>
     <ul>
       <li>
         <a href="#">Houston Astros         </a>
       </li>
       <li>
         <a href="#">Los Angeles Angels         </a>
       </li>
       <li>
         <a href="#">Oakland Athletics         </a>
       </li>
       <li>
         <a href="#">Seattle Mariners         </a>
       </li>
       <li>
         <a href="#">Texas Rangers         </a>
       </li>     </ul>
   </li> </ul>

In style element (<style>) within head element:

ul {
    padding: 0;
    margin: 0;
    list-style: none;
    }
  li {
    position: relative;
    width: 15em;
  }
  li ul {
    display: none;
    position: absolute;
    top: 1.7em;
    left: 0;
  }
  li > ul {
    top: auto;
    left: auto;
  }
  li:hover ul { display: block; }

  #dropdown3 li ul {
    margin-left: 15em;
    margin-top: -1.8em;
  }
  #dropdown3  li {
    border: thin solid navy;
    font-family: calibri,verdana,tahoma,helvetica,sans-serif;
    background-color: #ccf;
    }
  #dropdown3 ul li { background-color: #eef; }
  #dropdown3 a {display:block; padding: 0.25em;}
  #dropdown3 a:link,
  #dropdown3 a:visited,
  #dropdown3 a:hover,
  #dropdown3 a:active
    { text-decoration: none; font-weight: bold; }
  #dropdown3 a:hover { background-color: navy; color: #ccf; }