Where When Outcomes Demographics
Task 1 ยท Spatial Analysis
Where do stops happen?
Stop frequency by SFPD district, revealing which neighborhoods see the highest policing activity. Southern and Ingleside districts lead significantly.
# District Code Stop Count Share of Total Relative Volume
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Stop count by district (bar)
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District share (donut)
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Ranked districts โ€” horizontal bar
Task 2 ยท Temporal Analysis
When do stops happen?
Stop patterns by hour of day, day of week, and month. Peaks around midnight and the evening commute (5โ€“6 PM) suggest enforcement patterns tied to specific conditions.
By Hour of Day
Hour Stop Count % of Daily Total Volume
By Day of Week
Day Stop Count % of Weekly Total Volume
By Month
Month Stop Count % of Annual Total Volume
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Stops by hour of day (line)
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Stops by day of week
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Stops by month
Tasks 3 & 4 ยท Outcomes + Demographics
What happens after a stop?
Enforcement outcomes (warning / citation / arrest) broken down by stop reason and by race. BOLO/Warrant stops result in arrests 42% of the time. Black drivers face an arrest rate nearly 3ร— that of white drivers (2.6% vs 0.9%).
Stop Reason Total Stops Warning % Citation % Arrest % Search Hit Rate
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Outcome breakdown by stop reason (stacked bar)
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Search contraband hit rate by reason
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Arrest rate by race (grouped bar)
Overall Takeaway

The strongest cross-section finding is unevenness. Stops are concentrated in selected districts, cluster in recognizable time windows, and lead to different outcomes depending on why the stop happened and who was stopped.

That makes the StopAtlas story more than a set of counts. It is a way of showing that traffic enforcement operates through patterns in place, time, and procedure, which is exactly what the later interactive milestones should help users explore.

Interactive Ideas โ€” M3 / M4

How could these become interactive?