 <p>Short answer: Because DOS behaved this way, and <code>cmd</code> tries to mimic DOS.</p> <p>Originally, DOS had a 'current director' for each drive, so if you write <code>cd d:\folder</code> you change the current directory for the <code>D</code> drive.</p> <p>You can read more about this here: <a href="http://blogs.msdn.com/b/oldnewthing/archive/2010/10/11/10073890.aspx" rel="nofollow">http://blogs.msdn.com/b/oldnewthing/archive/2010/10/11/10073890.aspx</a></p>