Minneapolis Congestion Question

In the last few years, Minneapolis set a record for itself when it became the 10th most congested city in the US. Compounded with the rising number of potholes and slim prospects of better road conditions, the outlook for driving in the metro is rather glum. Whining aside, I'd like to get the bottom of this puzzling situation.

Becoming a worse city to drive in is not that usual for Minneapolis. In 2005, Twin Cities gained national attention by using creative ways to get people out of their cars during the work commute. Since then Minneapolis became the #1 city in the US for bicycling, but that did not have a significant effect on automobile traffic.

One possible answer is that persons that were laid off during the economic downturn found new jobs and are now driving to work, causing the congestion. Department of Numbers reports a sharp employment increase in 2008-2009. Star Tribune claims that congestion lessened in 2008 because of unemployment. These numbers don't seem to completely correlate, however, since the unemployment rate picks up after a large congestion decrease. MnDOT states that a likely cause of traffic slowdowns was the construction of the new I-35W bridge, when traffic was routed to other highways.

University of Minnesota's Institute on Race and poverty offers a different view of the picture. Data from commuters was collected from several employment centers. People with low income drove alone most of the time (70%), giving rides to others 10% of the time, and riding a bike less than 2%. This could mean that either they needed a vehicle to do their job, or they preferred to drive instead of using other transit options.
Another finding of the institute is that the people living in either downtown and West Saint Paul were much less likely to have a car than other residents. You can view the map here.

According to the 2010 census, Minneapolis population did not change significantly over the past 10 years. However, the metro area grew by 0.8%, or 207,000 people. This growth is footed by the suburbs surrounding Minneapolis. In fact, the metro population will swell by an additional million of people by 2030. From this and the fact that people living in areas farther from downtown are likely to have a car, we can extrapolate that some of these new residents drive to work. If 70% of them drive, there are almost 150,000 new drivers in the metro since 2000. During these 10 years, many teenagers also started driving, so this is a conservative estimate.

It is likely that the new suburban drivers are the cause of the congestion on Twin Cities highways. However, a larger reason is the 'car culture' in the USA. We like to drive and we are not willing to bike or walk to work. We don't always move close to work, traveling longer distances and spending more time in traffic instead. Part of this is lack infrastructure, but the most practical solution is education and incentives for commuters to use other means of transportation.