How many cars do Americans own per household? It might be a harder question than it appears to be at first glance. University of  Michigan Transportation Research Institute’s Michael Sivak found in a 2013 study that people are driving less frequently now than they were two decades ago. Meanwhile, public transportation, along with the flourishing sharing economy—such as Uber, Zipcar, and RelayRides—are on the rise, allowing people to get around without owning a car. On the other hand, the makeup of American households has become more diverse than ever.

The implications of more people opting to live in households with multiple generations, or invest in "forever homes" with aging-in-place features, could, in fact, reverse recent car ownership trends. Such sociological changes could lead to higher numbers of cars owned per household in some areas.  

To builders, the question could be even more complicated, because behind the ever-changing landscape of car ownership stands a new challenge for garage design. A garage, as most would agree, is a crucial component of a home. It can be very flexible in terms of design, depending on the size of the lot, style of the home, and width of the driveway. Is a two-car garage good for all? Or is there some kind of “go-small” trend taking place in the garage world? If so, is this a universal rule that applies to the entire country? Or, how much does car ownership differ from one state to another?

To answer all those questions above, we've created an interactive map highlighting car ownership per household in all states across the nation. (Unfortunately, District of Columbia is too small for you to see on the map, but is certainly no less important.) Our methodology was to pull data from the 2013 American Community Survey on tenure by vehicles across all occupied housing units in the nation. We have excluded renters in order to focus on home owners, and to give  builders better insight into consumer preferences in each market.

Among all states, homeowners in Wyoming are the most dependent on vehicles--only 1.6% of its homeowner units do not own a car. Wyoming is also the top state for multiple vehicles--39.07% of households own three cars or more. Therefore, builders in Wyoming might want to set aside a garage space that is large enough to house multiple vehicles (and also account for storage).

Top car-free state:

District of Columbia: 15.69% of homeowner units do not own a car

Top 1-car state:

District of Columbia: 50.55% of homeowner units only own one car 

Top 2-car state:

New Hampshire: 47.33% of homeowner units have 2 cars 

Top 3-car state:

Wyoming: 23.92% of homeowner units own 3 cars 

Top 4+ car state:

Wyoming: 15.15% of homeowner units own 4 cars or more

As high as 15.69% of homeowners in the District of Columbia do not own any vehicles, signifying that builders can focus on designing homes with a larger living area than is most often seen in big cities. Of D.C. households that do own vehicles,  50.55% only have one car, as opposed to 7.2% homes having three cars or more. In other words, accommodating one small-sized parking space rather than an actual garage would be optimal in the nation’s capital.

Across the nation, it's most common for a household to own two cars--over 40% of of households own two vehicles in all states but two. New Hampshire finds the largest portion, or 47.33%, of the state’s home owners with two cars at home, followed by Wisconsin, 47.20%. District of Columbia and New York, ranked to the bottom, have 39,76% and 26.55% households owning two cars, respectively.

 To see the complete data for our interactive map above, view the Google Sheet.