Image courtesy of Gualberto107 at FreeDigitalPhotos.net
Please for the love of goodness know where things are located and how long it will take you to get there with various transportation methods. Normally my rant of this type is about medieval or regency romance type settings in England where a distance can vary from one hour to several days ... by horse - to the same location in the same story - when the map says 20 miles on smooth roads originally installed by the Romans.
Today edit is a British author writing about America (rather than the other way around). Atlantic Ocean to Chicago by horseback is NOT five days. Horseback is not that much faster than walking when going through forested areas. And doing it while dodging zombies ... well, let's just say more like five weeks than five days.
Maps are your friends - USE THEM!
Writing/Reading Exercise: If your present work-in-progress or you present read is set in the real world, review distances for things.
Humans walk about 3 miles an hour, 4 miles an hour is a brisk walk and not sustainable over distance (except for infantry on a forced march). Horses go about 4 miles an hour steadily. And travel for both is usually limited to daylight hours - summer has much longer travel time than winter. Caravan and large groups need to start and end the day sooner than a couple of lone travelers. Bikes go 10 to 15 mph, and cars, when they first came out went the ridiculous speed of 20 miles per hour - equal to an easy day's walk in an hour! (Scientist were worried about our ability to breath at those speeds.)