A bubble chart visualizes the relationship between urban population growth and total mobile cellular subscriptions for the US, Canada, and Mexico, with each bubble’s radius encoding subscriptions per 100 people. The D3 v7 code loads CSV data, filters to three North American countries, and uses a log-scaled y-axis with d3.scaleLog. Circles are rendered as SVG elements with tooltips, using d3.axisBottom and d3.axisLeft for axes. Data comes from the Global Development dataset hosted on GitHub.