Today is the deadline for cities all around North America to submit their proposals to Amazon, which is looking for a spot to build a second headquarters. It's a huge opportunity considering "Amazon HQ2" is expected to bring with it as many as 50,000 jobs and tens of billions of dollars' worth of investment in whatever community the online ecommerce behemoth chooses. Here are a handful of cities which would make likely candidates, according to the words of Marty Pupil, president of U.S. Brokerage at Colliers International, a global commercial real estate services organization.

Austin

With an established tech identity and access to highly-skilled employees coming out of local universities, Austin would be a natural choice for Amazon HQ2. The quality of life in Austin is outstanding, and it offers a housing market that is far more affordable than Seattle or other top-tier gateway cities like San Francisco and New York. Austin infrastructure is strong with an international airport and, unlike other large Texas cities, a strong public transit system. Austin also is urban enough to already have in place the amenities, shopping and restaurants Amazon would want its employees to have access to.

Raleigh/Durham

It may be wise for Amazon to consider an East Coast location for HQ2 merely to spread out its network. Raleigh/Durham is a growing tech hub with an emphasis on biotech and life sciences, which has already helped the city attract some top talent that Amazon could capitalize on. The area also would offer employees a low cost of living and the company plenty of access to real estate, whether it would like to lease existing space or even consider a build-to-suit opportunity with a developer. One minor challenge for this region may be an infrastructure system that isn't as mature as some larger metros. There is no train system, but the area does boast a robust busing system and a highly-ranked airport.

Denver

This city has been on the rise for years, but landing a trophy like Amazon HQ2 would put it on par with metros like Seattle, Boston and Dallas. Quality of life and a business-friendly local government rank high on Denver's attractiveness. Developers have been very active in Denver through this cycle, creating a significant amount of newer projects Amazon could look to lease up in a city that is already full of restaurants, shopping and young professionals. In addition, Denver offers top-notch infrastructure, with a highly-regarded public transit system and access to what is already one of the busiest airports in the country.

Detroit

Detroit is a city many want to see return from the ashes. There aren't many cities that could offer Amazon a truly urban environment with an incredibly business-friendly local government and affordable housing. And, it would be a triumph for Amazon from a public relations standpoint. Yes, the company would get the urban setting and affordable real estate, both corporate and residential, in addition to international airport access. However, in one fell swoop, Amazon could be the catalyst for the rebuilding of one of America's great cities. One challenge for Detroit may be its public transportation system, which is not well developed and ranks very low nationally.

Washington, D.C.