There are basically 3 route options for driving from Whistler to the US. One is to follow Hwy 99 right through Vancouver and across the Douglas/Peace Arch Crossing at Blaine, WA to Interstate 5 in Washington State.

The second is to follow Hwy 1 east to 176th St in Surrey which is Hwy 15 (Pacific Highway) and across the Pacific Crossing to US Hwy 543 (Truck Route) and on to I5.

The third is to follow Hwy 1 further east to 264th St and turn south on Hwy 13 (Aldergrove-Bellingham Hwy) to the Aldergrove Crossing where the US highway 539 is called Guide Meridian Road. This one will take you to Bakerview Road where you turn west to the Bellingham Airport as well as I5.

The latter two look farther, but traffic tends to move along most of the day. Peace Arch can be backed up with traffic heading into the States for several hours.  On weekends and in the summer when people are travelling, the easterly two crossings have an advantage.

The Peace Arch route comes in at 2.5 hours, 207 km. The Pac Hwy one comes in at 2.5 hours, 205 km. The Aldergrove route comes in at ~3 hours, 213 km, all according to Google maps. Plus any border wait or traffic congestion anywhere. If Peace Arch has a 3 hour wait at the border the other two routes have an advantage. They don't get the same waits.

The following border web cams, during daylight hours here, show what live traffic conditions are like at the three crossings.

Border lineups

Government of BC border crossings