1. WA: Olympia

Answers:

1. For British Columbia, Washington [Olympia], and Oregon [Salem], name their respective capitols.
Not Vancouver for BC nor Seattle for WA
BC: think British royalty. WA: think Greece
BC: Person's name. WA: Take a major sports event, remove the last two letters, and add another to the end.
BC: feminine name. WA: sounds similar to a mountain

Female British monarch: that would be Victoria.

2. Until it was shut down indefinitely due to COVID, what was the only Washington State Ferries stop not in Washington State?
Not Greater Vancouver
Somewhere in BC
Pronounced the same as a major Australia city, only one vowel is different.
Person's name, could be either gender.

Sidney

3. What store in which city can you find the Rubber Chicken Museum and the World's Largest Rubber Chicken?
Not Powell's Books
Store is name of person and is located in WA
First name of person is same as a comedic comic book character. Major city.

Archie McPhee, Seattle. I would have accepted "Archie something".

4. In which city can you find the World's Tallest Tin Soldier?
Not Portland
Not the main city, but part of a Greater _____
Name doesn't suggest that it's old or to the east.
In BC

Located in Greater Vancouver: New Westminster

5. What is the name of the world's smallest park and in which city can you find it?
Arguably despite the efforts of some past provincial governments, the world's smallest park is not in BC
Major city. For name of park, think "grinder terminates".
Or maybe "pulp and paper or aluminum processor finishes". Not in WA
In OR.

Mill Ends Park, Portland

7. Which beach-sounding municipality is just south of Boring, OR?
Not Seaside.
Location has a [municipality name] Chainsaw, [municipality name] Bicycle, and [municipality name] Liquor, and in all three cases the municipality name might put you off the purchase.
Name is normally a one word adjective.
Also name of comic book sidekick

Sandy

8. In which business in which city can you find a vacuum museum?
Not a business with additional locations **outside the Pacific Northwest**.
Franchise in the general area, with this branch in a major city.
Not in BC. At some point the name of the business will be laid bare.
In OR

Stark's Vacuums, Portland. It used to be in a small corridor and had a wide range of vacuums. It was later downsized and the few remaining put on a wall. I think the newer version sucks.

9. Which light rail transportation in Seattle has just two stops?
Not the Sounder train.
One stop takes you almost right to the Space Needle
There is only the one train.

One and train, so Seattle Center Monorail

10. Which municipality unfortunately made the news when it was when it was discovered that some of its residents were engaging in what they considered to be romance with horses? I'm probably going to have to be a bit more vague with some of the clues than I would be for the other questions.
Not in BC
The last syllable is something that some animals have but not horses.
Three syllables
In WA

Enumclaw. There is a documentary called Zoo which uses beautiful music and imagery including of Seattle to try to evoke symapthy for the subjects. What it is careful not to do is show horse @#$%ing. Russell Hodgkinson of Z Nation fame played the deceased, "Mr. Hands" in renactments. If you want more details, you just need to Google "Enumclaw horse". You don't need to put in any other words into your search.

11. What is the largest municipality in Greater Victoria?
Not Victoria proper.
First Nations sounding name.
Two syllables.

Saanich.

12. What are light rail trains in Greater Vancouver, BC called?
Nothing that sounds like "subway".
Name suggests above ground, despite one of the lines being largely underground.
Two syllables, each a word normally, think "aerial locomotive"

SkyTrain

13. Where can you find the last Blockbuster Video?
Not in BC
Trying to guess this might drive you nuts. It might even...
Unless your body is paralyzed, it can do this..
In OR

Bend  (in one of the clues I was trying to point towards "drive you round the bend").

14. Which Seattle landmark can you find under a bridge?
Nothing related to grunge music.
Consider works of fiction involving bridges.
The attraction is a statue, and where it's situated is very relevant
Think folklore and under a bridge

The Fremont Troll. I would have accepted "a troll".

15. Which municipality is directly north of Portland, OR?
Not an Oregon location.
Shares name with a much better known Pacific Northwest city.
Shares a name with a major city, and there are not two municipalities with the same name in the state.
Shares name with a BC city

Vancouver, WA

16. Victoria, BC is on what island?
Not Victoria Island (and we hate it when people call the island that).
Shares name with a city not on the island.
Its city namesake is a major city.

Vancouver Island

17. Victoria, BC's Inner Harbour has two ferries going to Washington State. What are the two municipalities they go to, or if you prefer, come from? That is, each ferry stops at Victoria and only one other municipality.
Not Forks (sorry Twilight fans) or Port Townsend
One of the two locations is a major city, the other is two words and the second word is the same as the second word in a well known city in the US far south of the Pacific Northwest but still on the west.
Both locations are less than three hours sailing away.

Port Angeles and Seattle

18. In which district in Vancouver can you find a steam clock?
Not Granville Island
Think fuel
Two syllable word. Think "flatulent municipality that is smaller than a city"

Gastown

19. The Old County Market is known for having multiples of a particular type of animal on the roof. Which animal are they and which municipality?
Not horses
Location is hair item often found in bathroom, only with one letter duplicated. Trying to figure out the animal type might be very frustrating. It might even...
Animal commonly found on a farm. First three letters of municipality: think dove speak.

Goats, Coombs (in one of the clues I was trying to point towards "get your goat").

21. In which municipality can you find the headquarters of Microsoft?
Not Everett
East of Seattle but still greater Seattle.
First syllable is a colour.

Redmond

22. In which municipality can you find the headquarters of Fantagraphics?
Not in Oregon
Major city.
Somewhere in WA.

Seattle

23. In which municipality can you find the headquarters of Dark Horse Comics?
Not Beaverton.
While not in Portland proper, it's part of Greater Portland.
There might be happy days ahead if you can figure this one out.

Milwaukie (Happy Days was set in the similarly named Milwaukee, WI).

A couple more:
Dark Horse Comics:


Downtown Enumclaw: