Data

Trade area analysis: the numbers a tenant underwrites.

By Noah, founder of Endcap. Published August 1, 2026 · Updated October 10, 2026

Every retail flyer has a demographics table. Almost none of them say where the numbers came from, and a surprising share are simply wrong: a city-level figure passed off as a radius, a competitor's ring recycled from an old flyer, a "daytime population" nobody can trace. Tenants underwrite these numbers. Here is how to produce ones that survive scrutiny.

Why portal demographics miss

The demographic block that portals auto-generate is a black box: unknown vintage, unknown method, centered wherever the pin happened to land. We have seen published radius figures that were actually zip-code composites, rings labeled one mile that contained a quarter million people, and income figures a decade stale. A sophisticated tenant rep spots these instantly, and the listing's credibility goes with them.

The method: tracts, weighted to true rings

The census does not publish data in circles, so someone has to do the geometry. The defensible approach, and the one the professional data vendors use, works like this:

• Start from the exact coordinate. The front door, not the zip centroid. On a long block this alone moves the one-mile numbers meaningfully.
• Pull every census tract that intersects the ring. For a five-mile ring in urban Southern California that is typically 100 to 150 tracts.
• Weight each tract by how much of it falls inside the circle. A tract half inside the ring contributes half its people. Skip this and edge tracts distort everything.
• Aggregate the weighted values for population, households, aggregate income, and the income brackets. Averages come out cleanly; medians must be estimated and should be labeled as estimates.
• Sanity-check against published comps. If your three-mile ring lands within a couple percent of what the data vendors publish for a listing on the same corridor, you did it right.

When we built the listing for a corner suite in Buena Park (case study), this method produced 235,280 people within three miles, against published vendor figures of 236,000 to 242,000 for the same corridor. Close enough to trust, sourced well enough to print.

Traffic counts: go to the primary source

"High traffic corner" is folklore. Counts are data, and they are usually public:

• City GIS layers. Many cities publish average daily traffic by street segment, updated on a cycle. This is the count for the road your storefront actually faces.
• Caltrans Traffic Census. Annual average daily traffic for every state route and freeway, free, with history.
• Print the source and year with every number. "21,149 VPD, City of Buena Park GIS, 2025" reads completely differently than a bare "21,000 cars/day."

A number with a source is evidence. A number without one is decoration.

Present it like you mean it

The analysis only earns its keep if a prospect can absorb it in a glance. Three presentation rules we follow on every listing:

• Annotate the aerial. Put the counts on the roads they belong to, label the anchors, pin the site. One image replaces three paragraphs.
• One table, 1/3/5 miles, sources printed. Population, households, average and median income, median age. Resist the urge to include everything the census offers.
• Never repeat a number. If the hero says 63,000 vehicles a day, the table should be adding depth, not echoing.

The same numbers then feed the flyer, so the PDF and the page never disagree; how that document comes together is covered in our flyer guide.

If you want this handled rather than explained: offering memorandums & flyers and commercial real estate photography.