Unhappy that Mayor McGinn—facing shortfalls in the city budget—pushed the pause button on a plan to hire new patrol officers by year’s end, the Downtown Seattle Association took to the op-ed page of The Seattle Times to express its view that the city’s police force is short-staffed.

The DSA notes that back in 2000, Seattle’s population was 563,374 and SPD employed 1,264 officers—2.24 officers for every 1,000 Seattleites.

Ten years later, Seattle has 617,334 residents and 1,338 officers, or 2.17 officers per thousand residents. “We can’t sustain safe and vibrant neighborhoods with a shrinking police force relative to the overall size of the city,” wrote DSA representatives.

It’s an intuitive argument, but exactly how many police officers does a city of 600,000 need anyway?

UCLA professor of public policy Mark Kleiman, who last month spoke at a city-council–sponsored town hall on public safety, says there’s no generally accepted benchmark for police staffing levels. But he says a decent police-to-population ratio is 1.5 to 2 officers per 1,000 residents.

That puts Seattle well within range. And as Mayor McGinn points out, the number of major crimes committed in Seattle has tumbled in recent years.

Still, SPD’s latest stats indicate that in downtown Seattle, property crime is up. And with high tourist season underway, the DSA is likely to have more grist for its argument.