Where is the system wide PATH shell variable set in OS X?

I'd like to set the PATH shell variable for all users, but could not find where it is defined.

Having no export PATH in my .bash_profile, I have this:

/usr/bin:/bin:/usr/sbin:/sbin:/usr/local/bin:/usr/local/git/bin:/usr/X11/bin

Where is this the PATH shell variable defined?

On a shell level, the PATH variable is set in /etc/profile by calling /usr/libexec/path_helper. To add your own paths, you can add files with a path in it to /etc/paths.d/:

pse@Fourecks:~$ ll /etc/paths.d
total 8
-rw-r--r--  1 root  wheel  13 Jul 22 07:02 50-X11
-rw-r--r--  1 root  wheel  12 Aug 13 14:12 TeX
pse@Fourecks:~$ cat /etc/paths.d/TeX 
/Library/TeX/texbin

That's the safer way than editing /etc/profile, /etc/paths or any other system-provided file which may get overwritten with the next OSX upgrade.