In the INSTALL file there was a paragraph that address my issue.

BOOST configure switches for MIRA:
----------------------------------

If a simple "./configure" and then "make" fails at the linker stage, you might
need to perform the "./configure" with additional flags telling it where the
version of BOOST that you want to use is installed. Those flags would be
"--with-boost[=DIR]", "--with-boost-libdir=LIB_DIR" or
"--with-boost-thread[=special-lib]". On how to use these flags, please consult
the help given by "./configure --help" or the documentation of BOOST
(http://www.boost.org).

I did the line below and all is fixed! Voilà!

sudo ./configure --with-boost-libdir=/usr/lib

I answered my own question, but in the future if you have this problem just tell MIRA where to find the BOOST library. MIRA won't even let you 'make' until it knows where BOOST is located.