not getting paid for over time

i am paid by the hour for trucking and for running the bobcat for the company i work for. they recently have told me that they do not have to pay any over time or (time and a half) for trucking because i only drive in state lines, but they will pay me over time if im in the bobcat but only if im in the bobcat on the last day of the week which is thursdays for me, so the are saying if im driving truck on thursdays and i have worked over 40 hours i get paid just my normall pay, but if i was doing bobcat work say like snow removal on thursday and had more than 40 hours in the have to pay me time and a half. i live in north dakota and they keep telling me that this was a regulation in colorado and that i have to follow it. so lets say i worked an extra 10 hours moveing snow on a wedsday but on thursday all i did was drive i wouldn't get paid for time and a half. is this right or are they trying to screw me over. thanks

 

i haul grocerys and milk for a grocery store in minot and drive down to bismarck about 100 miles away to get the grocerys and bring them back to minot. nothing to do with agriculture. any more quistions just ask away.

 

is there any website or evidence i can take to them, because i have looked all over the internet and can not find any thing to support this.