Seattle may be the heart of the Puget Sound region, but the area’s arteries are carrying people further afield.

Consider that that Seattle isn’t much bigger geographically than its Eastside suburbs. It accounts for a steadily smaller share of King County’s population and commuter traffic increasingly heads out of Seattle during the work day. All this means that planning for transportation and housing needs to serve the entire region.

During last month’s deluge there were many comparison’s to Nov. 1933, the wettest month on record. A Seattle Times story about that era mentioned that Seattle then had 365,000 people, about 200,000 less than now. Meanwhile King County has swelled from 465,000 in 1930 to 1.8 million now. In other words, the city’s share of the total has shrunk to less than a third.

Traffic patterns have shifted even more. Going from Seattle to work on the Eastside is still considered the “reverse commute,” though in fact more traffic makes the trip. More vehicles go to the Eastside in the mornings during each peak hour (3,830 eastbound vs. 3,710 westbound) and return to Seattle in the evening (4,020 westbound vs. 3,580 eastbound), according to a state Department of Transportation study. Thanks to buses going downtown, more people travel to Seattle in the morning (6,810 westbound vs. 5,850 eastbound) and to the Eastside in the evening (6,390 westbound vs. 6,440 eastbound).

Some ways to address these patterns? The region could build a relatively inexpensive surface-and-transit replacement for the viaduct freeway, rebuild the 520 bridge for transit, significantly expand light rail and develop the Eastside rail line into a new transit corridor.