Crossing the Hoover Dam?

I've never been to Arizona and I'm planning on taking my first steps in the state near the Hoover Dam. I'll be driving from Las Vegas, NV. I know all the strict rules about crossing the dam, but I'm curious to know if I can just cross, pull over just across the Arizona border and then turn right back around or do I have to go the full nine miles to the check point before I can turn around and head back into Nevada?