MP: 18.45 Location: International Blvd and S 188th St, Seatac WA Taking 188th St to I-5 is a neat option for southbound travellers.   MP: 17.65 Location: S 200th St and International Blvd, Seatac WA Turning left on S 200th St takes you to I-5, the best option for Tacomabound Travellers. Neat old sign, too. … Continue reading State Route 99, SR 518 to SR 509/516