Twice the Space

The Seattle Convention Center campus sits at the uphill edge of downtown, where it meets Capitol Hill, First Hill and the Denny Triangle, and contains two buildings a block apart: the Arch, the original on Pike Street, and the Summit, which opened on Pine Street in 2023 and more than doubled the floor. Business did not double with it, so rooms sit empty. Both buildings belong to a public body, the Washington State Convention Center Public Facilities District, the District below.

I have argued, in the Commons, for filling the Arch with community events, to raise the floor of daily traffic on the side of the block that a convention fills for a week and leaves for a month. A proposal like that needs evidence. Which spaces are empty? Which are available, on which days, and what would a community booking displace? That turns out to be tricky to compute. The event log names rooms by whatever combination the organizer took, and the floor plan lists every configuration a room can be sold in as its own row, so a floor has to be counted once however it was sold. I tried it in May, from the event log alone, in Fell on Black Days, and got close; the figures that moved when the work was redone are corrected at the foot of that piece, dated. This is the better answer.

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What I built

The District's two floor-plan booklets, the Arch's and the Summit's, went into Insights, the site the gold button above opens, as documents with every page rendered, and every dimension, ceiling height and capacity, and every square footage the booklets print, is a figure read from a table printed under a floor drawing, citing that page. On top of them sits a model of the two buildings: 15 floors, the Arch's counted as two structures, 705 Pike and 800 Pike, because the booklet draws them on separate pages and a skybridge joins them; 372 spaces, of which 120 are combinations, which the page calls configurations, a hall sold whole or as its halves, and each combination is recorded as the parts it is made of, so a floor is counted once however it was sold; and eight circulation zones, five at the Arch and three at the Summit, each with its own entrance, because the question a neighbor asks is not which room but which door.

The District's own event log, produced with the public-records response of May 15, is joined to that: 952 events and 13,946 bookings of a space, from 2019 through 2025, reduced to one row per space and day, marked live when the event was running and occupied on any day it was held, setup and teardown included, which is the difference between empty and available. From those rows the buildings page answers the question for any year and any part of the building, in events, in days with an event on, in days occupied, or in floor-days, square feet times days, the unit that lets a big hall for a short booking be compared with a small room for a long one.

A walk through the page

The same chart set to 2025, by floor, floor-days used, with the line beneath the controls reading: Floor-days used on each floor of the Arch and the Summit, in 2025. Each number is millions of square-foot-days. The Arch's floors are drawn as a stack on the 705 Pike side, Level 6 Ballrooms and Meeting 15.7M, Level 5 0.1M, Level 4 Exhibition Halls 40.6M in the darkest shade, Level 3 Meeting Rooms 1.7M, Level 2 Meeting Rooms 1.5M, and across Pike Street the 800 Pike stack, Tahoma Level 3 1.7M, Chelan Level 2 0.6M, Yakima Level 1 0.3M, and below the street line Skagit Lower Level 0.7M. The Summit's stack on Pine Street: Level 5 21.7M, Level 4 11.1M, Level 3 11.5M, Level 2 25.0M, Level 1 2.7M, and below the street line Level EX 24.4M. The legend reads cold to hot, against the busiest zone, and a note defines floor-days: square feet multiplied by the days they were occupied. — The same year by floor, in floor-days. The exhibition halls carry the building; the four floors at 800 Pike together used less floor than the Arch's Level 6 alone.

Switch the chart to floors and the shape of the problem is plain: at the Arch, Level 4's exhibition halls used 40.6 million floor-days in 2025 and the four floors across the street at 800 Pike used 3.3 million between them. Click a floor, say the Tahoma level across the street at 800 Pike, and its page opens, with every room listed for it, its square footage, dimensions, ceiling height and the four seating capacities, each row the booklet prints citing its page.

The Tahoma Level 3 page on the Buildings site, scrolled to its table of spaces. Columns: Space, Sq ft, Dimensions, Height, Theater, Classroom, Banquet, Conference, Cited. Rows: Tahoma Level, a configuration of other rooms, 31,000; Tahoma 1-5, a configuration of other rooms, 19,046; Tahoma 3-4, 8,366, 94 by 89 feet, 13, 828, 396 to 528, 520, cited p.11; Tahoma 5 plus Foyer, 5,916; Tahoma 1-2, 5,208; Tahoma 3 and Tahoma 4, 4,136 each, 94 by 44 feet, 408 theater, 240 banquet, 104 conference; Tahoma 5, 2,856; Tahoma 2, 2,604; Tahoma 1, 2,542; Falls Suite, 558, 18 by 31 feet, 9 feet high, 6 conference; nine of them with p.11 in the Cited column; the two configurations the booklet does not print carry none. Above the table, the foot of the booklet page itself is visible, with the District's phone number and the line Arch, Floor Plans, Capacities, and Dimensions, January 2024. Beneath, a note explains that dimensions, ceiling height and the four seatings are read off the capacity table the plan prints under the drawing, and that a configuration is the same floor as its parts under another name, so only the parts are summed. — One floor: eleven rows for the Tahoma level, ten printed by the booklet and one, Tahoma 1-5, a name the event log uses; the combinations marked as such, and the nine the booklet prints citing page 11.

The citation modal open on page 11 of the District's Arch floor-plan booklet, headed SCC Arch floor plans, capacities and dimensions (2024-01-22), p.11, with Fit, 100%, 200%, Text and Close buttons. The page shows the Tahoma Level 3 plan, five numbered rooms and Falls Suite around a central lobby with escalators marked To/From 4F, and below it the booklet's own capacity table for the meeting rooms, Tahoma 1 through Tahoma 5, Tahoma 1-2, Tahoma 3-4, Tahoma 5 plus Foyer, Falls Suite, and Tahoma as Exhibit Space, 31,000 square feet, 124 ten-by-ten booths. The footer reads Seattle Convention Center, 2024-01-22, Page 11 of 12. — Click p.11 and the page opens: the District's own drawing and its own table, the source of every figure in the row above.

What it shows

Set the page to 2025, by zone, days with an event on, and it shows four things.

The chart on the Buildings page headed How much each part gets used, set to 2025, by zone, days with an event on, with the line beneath the controls reading: Days with an event on, in each zone of the Arch and the Summit, in 2025. Each number is calendar days, out of 365. The Arch's five zones are drawn as blocks on either side of Pike Street: Ballrooms and Meeting Rooms on Level 6, 144 days; Atrium and Hall 4AB on Levels 2 and 4 west, 135; Skybridge and Hall 4EF on Levels 3 and 4 east, 154; and across the skybridge at 800 Pike Street, the Tahoma Level, 55, and Skagit, Yakima and Chelan, 44. The Summit's three zones on Pine Street: Meeting rooms and Ballroom, 165; Summit Lobby, 142; Exhibit Hall and Flex Hall, 144. A legend reads cold to hot, against a full year, and a line beneath explains that height is floor area, so a zone that is large and quiet does not read like a cupboard that is busy. — 2025, days with an event on, by zone. The two blocks on the far side of the skybridge are 800 Pike; the lower one is the floors with the street door.

The big halls are busy. The Arch's exhibition halls and ballroom level and the Summit's halls each had an event running on roughly 150 days of the year.
The Arch's halls were busier in 2019. The same Arch zones each had an event running on over 200 days that year, and were already at about 150 in 2022, before the Summit opened.
The 800 Pike side of the Arch is the empty side. Across Pike Street from the main building, the floors with the street door had an event on 44 days in 2025 and no event on the other 321; the Tahoma level above them had 55.
On most days one building has no event on. The Arch had an event somewhere in it on 194 days and the Summit on 172, and both had something on together on 113.

None of that is a criticism of the people who book the building. Conventions are sold years out and the big halls are the product. The empty space is in the parts of the building a convention does not need, on the days between conventions, and it is concentrated on the side of Pike Street with the smallest rooms and the street entrance.

Why it matters

Now that the problem can be seen, the mitigations are easier to think about. A community booking on the 800 Pike street floors on a Tuesday in August displaces no event; the page shows how few days a year those floors are in use. A recurring public program in the atrium on the days between conventions can be sized to the number of days the atrium is actually free, which the page also shows. And the argument about whether the Arch is empty, which has been conducted in adjectives, can be conducted in days and square feet, from the District's own records, with every figure opening the page it came from.

I expect the District and its partners, the event hosts, the caterers, the hotels, and the neighborhood, will find this useful too, and as a member of the extended SCC family I am happy to make it available. Go to the buildings page, pick a year and a zone or a floor, and click any space: the page of the booklet that draws it opens, at full size, with the capacity table read off that page. If a number is wrong, the page will show you, and the form is where to say so.

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Sources. The District's floor-plan booklets for the Arch (January 22, 2024, 12 pages) and the Summit (April 13, 2026, 16 pages), and its event log, produced with the facility-utilization records response of May 15, 2026; all three are the District's records and are cited, not hosted. Bookable floor is the sum of the booklets' smallest sellable spaces, lobbies included: 380,371 square feet at the Arch and 471,826 at the Summit. Every day count and floor-day figure above was derived on September 13, 2026 from the Insights database, and the method is on its buildings page. Revenue is total operating revenues from the audited financial statements: $37.1 million for 2019 and $61.3 million for 2025. Every calculation can be redone from them.