reading the signal…
Signals / Object / Street-level imagery
in San Francisco, CA·counted·382 all time
Swallows are small, agile birds, typically shown flying with pointed wings and forked tails.
Counted, not streamed: Swallows has no time series, so it is read as a footprint across places. All-time count by city.
Things that physically exist: street furniture, signs, buildings. All-time counts.