There are 3 routes out of McCarren to the strip, downtown, Green Valley, etc. The 1st is the exit taking you right to Tropicana Blvd. and an easy route right to the strip. The other is the bypass which connects to I15 which is the preferred route if you are a resident of Summerlin or anywhere in the far north part of the valley. The 3rd will take your south through Green Valley to Henderson.

The bypass starts with a tunnel before it connects to the interstate and the taxi drivers love this route because it adds around $4-8 to the cabfare depending on what your destination is. I know this because I drove a Vegas taxi for 3 years.