The 2000 Census: I-5 drives population increase

Fed a steady diet of asphalt and concrete, the cities that line Interstate 5 from Canada to Oregon have grown thick and broad over the past 10 years, sprawling over additional land more than twice the size of Seattle's 88-square-mile footprint.

You can see it in Bellingham, where 500 more people live in each square mile than in 1990. And in Everett, which has swelled by two square miles in the 1990s. And in Clark County, the state's fastest growing, which exploded, growing 45 percent as Vancouver became one of Portland's most affordable suburbs.

The story of modern growth in Washington is to some extent the story of I-5. Originally intended as a connection between distant cities, it increasingly has become a clogged artery, the magnet for much of the state's growth. Planned in the 1940s as a toll road through the state's most populated cities, the freeway moved people so well that it became one the state's most effective, albeit unintentional, growth planners -- a seed farm for suburbs.

Consider this: Before the 1960s, roughly half of the state's population lived within a few miles of what is now the I-5 corridor. Now, 68 percent of all Washingtonians do. And since the highway's completion 30 years ago, 78 percent of the state's new growth has occurred no more than 10 miles from its shoulders, and 3.9 million people live within 15 miles of the interstate.

P-I Graphic
View a special graphical presentation of I-5 corridor growth, including population changes from 1990-2000 in cities and towns along the corridor. In GIF format (80K) or high-definition PDF format (329K).

Bob Schuster, who as a newly graduated engineer worked on the I-5 project from its start in the 1950s to its completion at the end of the 1960s, said the builders had no idea how I-5 would change the region.

"We didn't really think about how it might drive growth," he said. "That just wasn't in our calculations."

But the 2000 Census reveals what every I-5 commuter has complained about for years: Cities along Washington's north-south freeway have become more crowded at a faster rate than have towns elsewhere.

All of the 48 cities along I-5's 280 miles between British Columbia and Oregon added population in the past decade, and only five failed to bulk up by adding more people per square mile.

It isn't simply more high-rise buildings in Seattle's Belltown and Capitol Hill anymore. While the number of people crowded in the Emerald City -- 6,717 in each four-block area -- easily exceeds the crowding in the rest of the state, smaller cities like Lynnwood and Des Moines are seeing urban-style growth at about 4,000 people per square mile.

Tukwila, for example, has 400 more people per square mile than it did a decade ago. Tacoma has 200 more people in the same space. Kent shows an additional 1,000 people within a similar footprint. In Vancouver, which has grown from 46,000 to 143,000 in 10 years -- a 210 percent growth rate assisted by aggressive annexation -- 3,354 people live in a space that held 345 in 1990.

Clark County Commissioner Betty Sue Morris said the growth has been good economically but tough on people who have lived in the county for many years.

"It's been very difficult for some," said Morris, herself a "newcomer" at 30 years. "This community has grown faster than anyone expected."

Some experts say the state's 1990 Growth Management Act is partly the reason for the denser, faster growing cities along the interstate during a decade that saw more than 1 million more people pour into the state. Had it not been in place, they say, many more miles of the I-5 corridor would be packed with a long, narrow city of suburbs.

In the Puget Sound region, for example, the I-5 corridor cuts through the heart of areas designated as "urban" for zoning purposes. Under the act, urban areas are supposed to absorb the bulk of the growth to protect rural and forest lands. The bottom line: growth has been concentrated near the interstate because some counties, such as King, have tight building restrictions make the corridor the easiest place to develop.

King County Councilman Larry Phillips, a Democrat who has worked for years to create and modify the county's growth management plan, said the denser growth in the state's most urban areas means growth is happening as it should.

"We basically pushed growth to places like the I-5 corridor faster than it would have occurred (without the plan)," he said, adding that it helped "stop sprawl."

Sort of.

What it has done in some cases merely is shift it. Matt Erickson watched it happen when tight land use controls in Oregon forced new residents across the Columbia River, into sleepy Clark County.

When the Ericksons established their farm near Vancouver in 1898, the town was just a couple of thousand people and plans for I-5 were four generations distant. For a century, the family, one of the oldest in Clark County, grew berries and wheat, raised cattle and generations of farmers on several hundred acres north of town.

Now, it's part of town. And on a parcel of the land where his father, grandfather and great-grandfather grew strawberries, the Ericksons have grown a subdivision.

"It's kind of sad when you have to sell your land to make money," Matt Erickson said. "But it is a lot more profitable than farming."

Counties along the interstate also grew at a slightly faster rate than have counties elsewhere, when compared with the state as whole. The nine counties that stretch from Canada to Oregon along the interstate grew 22 percent, compared with 20 percent for the non I-5 counties.

"It stands to reason that where you have major roads, the growth will go there," consultant Tom Rubin said. Added Phillips, "In King County, growth was going to go there, anyway. We just helped focus it a bit."

There are signs that I-5 will remain a development magnet but that other parts of the state are taking on a greater share of growth than they have in the past. In the state's agricultural belt, Sunnyside grew at 23 percent, Yakima at 30. Along the Interstate 90 corridor, expansion in Issaquah and North Bend rivals that of I-5 cities. And as the I-5 corridor becomes increasingly built up and congested, and as cities expand to absorb and develop still more of the open space along the freeway, that effect likely will increase, transit and growth experts said.

"It's a good road and really did its job very well for the past 30 years," said Schuster who also worked on the I-90 project in his decades with the state Department of Transportation.

P-I reporter Mike Lewis can be reached at 206-448-8027 or mikelewis@seattle-pi.com