According to the bash man page, .bash_profile is executed for login shells, while .bashrc is executed for interactive non-login shells.
Mac OS X runs a login shell by default for each new terminal window, calling .bash_profile instead of .bashrc.
Setup your PATH variable in .bash_profile
vim ~/.bash_profile
correct PATH variable with below single line(which is working fine as per the question)
export PATH=/usr/local/bin:/usr/local/sbin:/usr/bin:/bin:/usr/sbin:/sbin