About a year ago, Apple announced a huge change to Apple Maps. It wasn't about new features in the Maps app (although there are new features coming in iOS 13), but rather a complete review of the basic map data. Buildings, rivers, roads, vegetation; the whole thing is far more detailed and accurate in the new maps.
Apple began rolling out new mapping data to Northern California just after its announcement, with a promise to continue rolling out new maps to the rest of the United States "over the next year. “Southern California and Hawaii followed at the end of 201
Now the new maps are rolling out to Texas, Louisiana and Southern Mississippi. If you live in these places, you need to notice new maps right away – you don't need to download a new iOS update.
Updated 08/13/19: According to MacRumors, the new maps are now rolling out to several areas in the northeastern United States, including Maine, New York, Washington DC and Pennsylvania.
Since the introduction of Apple Maps in iOS 6, the company has relied on data provided by a variety of external sources, which it then combined into one unified map. This helped Apple get the mapping project off the ground quickly, but has often resulted in less than stellar details and made it difficult to quickly make corrections. Apple's new maps rely on data that Apple has full ownership and control over. It's far more detailed and accurate, and Apple can quickly make adjustments to fix errors and keep the map up to date.