[wwmiv]

A legend:

county fill color: more color, less white = a higher share of the county's residents commute into the core

county border color: more white, less color = a higher share of the county's residents commute into the core EXCEPT those residents commuting into the county itself. Obviously this will only make a difference for those counties that are a core county themselves. Thus, core counties with more color borders comparatively LOSE more of their residents during the workday than those core counties with comparatively less color borders (though keep in mind layered county borders will obscure things slightly, but this is deliberate). Apart from core counties, this visual choice was made to contrast with the fill color so that it can be more easily visually read.

county fill opacity: more opaque = the county's commuters in the core contribute more to that core's daily workforce. This is selected on the estimate of the number of commuters into the core being statistically distinguishable from zero at a 95% confidence level. Thus, counties without a fill color likely have no commuters to that core. An adjustment is made so that MSAs with a higher daily workforce appear relatively more opaque than those with smaller workforces.

county border opacity: more opaque = a higher ratio of working residents who commute to the core versus those who commute within-county for work. This is selected on having an estimate that is above zero. Thus, counties that have no workers that commute to the core won't have borders or fill. conversely. However, counties that have a non-zero estimate of the number of commuters to the core that is statistically indistinguishable from zero will have opaque borders, but without any opaque fill.

county border width: wider = a higher number of working residents into the core.

The fill opacity and color choices were made so that you can layer them and make some useful APPROXIMATE visual comparisons.

The border opacity, color, and width choices were made to visually approximate the highway network, which seems to me to be a common modern heuristic of economic connections.

Furthermore, the counties are clickable and have popups with their info.

A 390-MSA map would require me getting server space to run the processing of the VERY data intensive map, and I don't have that $ right now.

What specific color scale a city is placed in currently conveys no information (and is currently done randomly). That being said, I'm going to be changing to be a rainbow gradient where redder equals more populated and bluer is less so.