The 2016 Mancelona, Michigan, population is 1,365. There are 1,361 people per square mile (population density).
I just wanted to add that clothes to wear at a wedding should be formal for the most part. A dress to wear to a wedding should include a simple cocktail dress preferably of silk material. Shoes to wear to a wedding include standard pumps or stiletto heels. Weddings are formal events and the attire should reflect it.
If your wedding is an evening wedding, guests should know this, since it's a typical rule of etiquette. You can write on the invitation, Black tie invited so that your guests know that it's a formal wedding. Based on your description of what you want them to wear, this is considered formal wear.