I'm the navigator when we rent a vehicle and ramble on our travels, so reading road maps is something I've gotten fairly good at.
Why make an effort with a road map when you can use the latest GPS equipment? Well, for one thing, road maps give you the big picture. Lay a map out on a table, and you can see the whole country or region. It makes planning your trip simpler.
And what about when you're on the road? Can't you just program the GPS and forget about it?
GPSs are OK, but they do have their down side. They may take you right through a busy city instead of going around it. The GPS chooses the "shortest route". It may not be the fastest...
May I contend that a navigator reading road maps sometimes comes in handy?!? We had this happen trying to find the Des Moines Airport in Iowa recently... Reading the roadmap and ignoring the GPS, we avoided driving through the city.
We had foreign friends who recently relied on their GPS to find their motel just outside of Yosemite National Park. The GPS insisted that their motel was 11 miles into the forest..... twice! TWICE they drove through town... right past their motel and into the forest. The third time, they started reading road maps and looking for themselves instead of relying on the machine, and guess what... They had driven right past their motel those first two times, just staring at the GPS... had they looked on the side of the road, there it was!
Sometimes you can get by with a map that isn't really a road map! We were traveling in Mali, West Africa one time with a car and driver. He was a very good driver... that's what we had asked for... which is whole different story....
So yes, he was a very good driver, but he had not traveled the country. When we left Mopti, he turned the wrong way. I was following along on our National Geographic map of the country, and it looked to me like he had turned the wrong way for Bandiagara. At first he said he was on the right road, but when he stopped to ask. Sure enough, we were on the right road.... going the WRONG way. Good thing I know something about reading road maps!
In the U.S. you will find that major roads are numbered with odd numbers going north and south... and even numbers going east and west. As freeways bend around cities this might look confusing. Look out to destinations beyond the city you are close to... that way you can tell whether you need to get on the northbound or southbound direction.
Traveling in Europe and other countries, maps will sometimes tell you the direction you're traveling by naming major cities the highway is going to. Again, look out beyond that small section of the map toward the edges, so you'll know which turn to take.
Major roads are in bolder lines, small roads are in thin black lines. Those small "black line" roads are scenic and fun to travel, but reading the road maps and finding your direction is more of a challenge to the navigator. We contend that if you get used to reading road maps, you can get anywhere!