This is via reporting in Willamette Week, which has kind of a libertarian bend, not as "liberal" as some alt weeklies.
...using cellphone GPS data to see how many people are returning to businesses, bars, restaurants, and other attractions in 62 downtowns around the county as the COVID-19 pandemic ebbs.
In the latest period, March through May of this year, Portland came in 60th, with a recovery value of 41% compared with pre-pandemic activity. Only San Francisco (31%) and Cleveland, Ohio (36%) fared worse. Salt Lake City topped the list in terms of people returning to downtown at 155%.
Berkeley researchers get the data from a company called SafeGraph Inc., which tracks 18 million smartphones in North America and reports visits by people carrying those phones to businesses, offices, shops, restaurants, parks, community facilities and stadiums.
“Either way, a lively debate is emerging about whether the pandemic will lead to a full-blown, 1970s-style urban crisis or more of the adaptive bounce back we saw in many downtowns after the Great Recession,” they (unattributed researchers) said.