Interesting points, though a couple small issues. Chicago and the Bay Area both have more than Houston, and Atlanta is way down on the list. Nowhere near third. Houston is also no Seattle or Toulouse when it comes to Aerospace. For that matter, I wouldn't put it on par with L.A. or Montreal. Probably more comparable to Wichita.
My information was a bit out of date.
The list I quoted was from 2007. (1. NYC, 2 Houston, 3 Atlanta, 4 Chicago, 5 Dallas).
The 2009 Fortune 500 rankings aren't much different, though (1 NYC, 2 Houston, 3 Dallas, Atlanta & Chicago tied at 4&5).
Being the home to the Space Center, NASA's largest facility, clearly places Houston as one of the World's premier aerospace locations. Boeing's also gradually leaving Washington. Ever since they bought McDonnell Douglas they have been moving towards the US interior. Just last week, due specifically to labor tensions in Washington, they announced they were going to build a parallel 787 assembly facility in South Carolina.
None of this is to say that Houston is the be all and end all of employment opportunities, but if you listen to nobody but Richard Florida, one would think that the Houston economy is based on nothing but Arby's franchisees and rodeo stadium staff. In fact census data shows Houston (as well as cities like Austin & Dallas) has become one of the biggest importers of college graduates in the USA and there are no shortage of surveys ranking it among the best places for college graduates to locate. This is despite a total lack of the amenities that some urban thinkers suggest are key to urban growth.
While partly true, major infrastructure investments in Europe like public transit, etc, are a boon for lower income residents. The European Union has a much lower income disparity than even Canada, so public realm improvements benefit everyone.
I'm a bit skeptical about infrastructure's economic benefits writ large*, but I don't think I suggested anything like that earlier. Immigration and infrastructure spending don't have any direct correlation in my mind.
*Or, at least, there is a point of diminishing returns with infrastructure. I think you get cases like Japan, where all manner of useless infrastructure projects get funded. Airports built in the ocean to handle nonexistent traffic, the world's longest tunnel built to connect a sparsely populated island, bullet trains to nowhere, highways to nowhere on top of that, needles dams and all manner of other project. Most of these projects have surprisingly low value to society, and just ended up giving the Japanese a nearly 200% debt/gdp ratio. On the other end of the spectrum is a place like Lagos, where there is clearly a lack of infrastructure. Toronto, I think, has a good middle point.