I concur with TaxGuyBill, you count from your primary job until you reach the shipping facility.
If you go to 2 or more job sites in a single day then the additional trips are deductible as a business expense. For example you leave home drive 5 miles to the 1st job (you regular/primary job) then drive 10 miles to the 2nd site and then 3 miles to the shipping facility. At the end of the day you drive 15 miles home. Only the 13 miles between jobs is deductible. The first trip in the morning, from home and the last trip at night back home are considered commuting and are not deductible.
