Franklin County was the fastest-growing county in the state between 2018-19, with Benton County nipping close behind at No. 3.

Kennewick ranked No. 5 in the state for population growth, adding 1,820 people; Pasco ranked No. 8, adding 1,700 people; Richland ranked No. 11, adding 1,530 people.

The Tri-City area’s population grew by 2.25 percent – or

6,520 people – over last year for a total of 296,480.

That’s up from 289,960 last year, according to the state Office of Financial Management’s data released June 28.

Here’s how Benton and Franklin counties’ cities grew between 2018-19:

• Benton City: 3.4 percent growth for a total of 3,520 people.
• Richland: 2.8 percent growth to 56,850 people.
• Pasco: 2.3 percent growth to 75,290 people.
• Kennewick: 2.2 percent growth to 83,670 people.
• Connell: 0.73 percent growth to 5,500 people.
• Prosser: 0.32 percent growth to 6,145 people.
• West Richland: 0.13 percent growth to 15,340 people.

The two smallest cities in the two counties, Mesa (population

495) and Kahlotus (population 165), showed no year-over-year growth.

Here’s how Benton and Franklin counties grew between 2018-19:

• Franklin County: 2.3 percent growth to 94,680 people.
• Benton County: 2.2 percent growth to 201,800 people.

The state’s year-over-year population grew by an estimated 118,800

people, a 1.6 percent increase over the past year, to more than 7.5 million,

according to the state’s annual estimates.

Migration is once again the primary driver behind

Washington’s population growth, according to the state.

Between 2018-19, net migration (people moving in versus people moving out) to Washington totaled 90,100, up by 3,300 from last year. Net migration accounted for 76 percent of the state’s population growth, with natural increase (births minus deaths) responsible for the other 24 percent.

This year, 69 percent of state population growth occurred in

the five largest metropolitan counties: Clark, King, Pierce, Snohomish and

Spokane — down from 70 percent in 2018. However, momentum continues to shift to

other metropolitan and nonmetropolitan counties: those with populations between

100,000 and 300,000 saw their share of growth increase by 1 percent to 19

percent while the share for counties under 100,000 people remained at 12

percent.

The April 1 population estimate for Washington’s incorporated cities and towns was 4.9 million , an increase of 74,400 people from the prior year.

Seattle’s population increased by 16,900 people for a total

of 747,300.

Washington’s population has grown by 821,900 people since the last decennial census on April 1, 2010. The state has grown by an average of 91,300 people per year this decade, exceeding 83,000 the previous decade. King County is the main contributor, with total growth of 295,100 people over nine years, compared to 194,200 people between 2000 and 2010.

Housing growth

The state added 44,900 housing units in 2019, compared to

42,600 in 2018, an increase of 5.4 percent.

Of all new units built in the past year, 54 percent were multi-family.

The state’s housing stock has grown by an average of 31,700 units per year since 2010, 27 percent below the prior decade’s average of 43,500 units per year.

More than 71 percent of all new housing units this decade were built in one of the state’s five largest metropolitan counties.

King County leads all counties with 104,500 new housing units, or 37 percent of the state total since 2010.