Defining Main Street: The Nostalgia. Let's end where we began, with Sinclair Lewis. Main Street was the most influential component of American urbanism for more that a century. Do you think it will ever be eclipsed by nostalgia for strip malls, retail strips, big-box stores, or shopping malls? 
Defining Main Street: The Post Office. You can buy local goods and services along Main Street, but one particular federal service has been part of the line-up since colonial times: the post office. A declining number still boldly display the name of the towns they serve. If your building has been stripped of its toponym, work to bring it back: Be like Ogden, Illinois. 
Defining Main Street: The Pet Groomers. Would you say that pet groomers and their ilk are recent additions to Main Street or old standbys? Their ilk? Pet supplies, doggie day care, vets, pet insurance?
Defining Main Street: The Hobby Shop. The hobby shop takes different personas in different places. Here it is a quilt shop, a place where customers can buy patterns and materials to make their own quilts. (plus classes and books). What big-box stores have taken the place of the hobby shop in modern suburbia? 
Defining Main Street: The Clothing Store. September arrives. The school year begins, Where do you go the get back-to-school duds? Main Street of course. That is, until shopping centers offer a wider variety of styles and options, And, until the bonds of geography are cut by automobility. Here's a clothing store that has made the transition to a new market. 
Defining Main Street: The Insurance Office. Again, let's not ignore the more mundane: establishments like the insurance office. And, humor always helps to attract attention. What other elements of Main Street culture might also be over looked? Attorneys? Funeral homes? 
Defining Main Street: The Real Estate Office. As we review of the elements of Main Street, let's not ignore the more mundane: establishments like the real estate office. There when you need it, invisible when you don't.