It sounds crazy, but all over the United States there are houses that are assigned with, what we call, fractional house numbers.
This picture is one I snapped in Louisville, Colorado in the spring, trying to avoid small talk at a kids birthday party. And yes, you are seeing the address correctly, it's 721 ½ Front Street.
Most people don't notice these fractional numbers of course. They are rare, but if you keep your eyes open you can spot them, usually in older neighborhoods. There are 377,089 "½" address numbers in the US, that's less that 0.2% of the total. There are also 7,302 address numbers that end with "¼". Other fractions also exist, but the numbers quickly drop off a cliff and descend into small hundreds. While these might seem statistically insignificant, they are all important.
You see, while this might seem like a total edge-case numerically, I've seen a lot of address processing systems get them wrong. Some treat the fractional part as unit numbers i.e. 721 Front St, Unit 12. Others remove the extraneous characters i.e. 72112 Front St. And then you get the systems that will simply ignore the ½ because it's been expressed as a Unicode symbol (½ versus 1/2). I've even seen some system convert 721 ½ to 721.5.
Getting it wrong is an opportunity for fraud and many other sources of lost revenue.
Fractional house numbers come into existence for 3 key reasons:
First, to accommodate new buildings in an existing neighborhood. If a new building is constructed between two existing buildings, it may be assigned a fractional house number to avoid disrupting the existing numbering system that didn't leave space. For example 721 ½ Front Street is between 721 and 722.
Second, if a parcel or lot is subdivided into two or more smaller parcels, one (or each) of the new lots may be assigned a fractional house number.
Third, they accommodate different types of buildings on the same parcel. For example, if a house and a commercial unit are located on the same lot, one of them may be assigned a fractional number to distinguish it from the other.
This latter case is what happened for our address in Louisville. 721 and 721 ½ are on the same parcel of land. 721 which is accessible from Front Street and is zoned as a small office space. While 721 ½ is accessible by the alleyway behind the property and is zoned as a residence.
Keep your eyes open and if you spot one of these rarities, send me the photo please.