Be on the Right Side
Until the end of the 1940's it was considered improper for a man to walk beside a lady whom he was with on the sidewalk. His proper place was a comfortable two paces behind. The rationale was that he would be in a better position to “protect” her from that vantage point - similar to a “guardaspalle” in Italian (which translates to “back guard”) or the phrase “I have your back” in English.
Emily Post states that “it used to be that a man escorting a woman on the street walked on the inside so that if waste were thrown out a window it would hit him and not her. Then when sanitation became recognized as important and people stopped tossing their waste into the street, custom changed and a man escorting a woman walked on the street side to keep her from being splashed by mud thrown up by carriage wheels or horses’ hooves."
Even though our streets are now paved and horse carriages have been replaced with vehicles, it remains a gentleman's position to eliminate the risk of a puddle splashing up on a lady on a rainy day. We all know the scene of a city bus splashing a pedestrian in the NYC streets far too well. A gentleman should walk on the curbside to protect a lady not only from a puddle but also a biker, a car, a construction site, or any other sidewalk danger. Awareness of what is going on around you ensures that the other person doesn't have to walk with caution or fear. Personally, I find myself switching sides depending on which side I consider to be the most protective from any threat - be it a puddle on the street or an open cellar door of a store.
One thing is for sure, I am definitely thankful that culture now makes it acceptable to always walk NEXT to my lady.
Be a gentleman and put others first.