Ed Stoddard is a Reuters senior correspondent.
One of the most striking things about the drive from the Congolese border to the Rwandan capital Kigali is the utter lack of garbage.
It is especially jarring if you have just come from the Congolese border city of Goma, where uncollected trash is scattered all about and rotting under the tropical sun.
The contrast says a lot about the two countries.
In Democratic Republic of Congo (DRC), the failure of the state is on a scale as grand as the country's massive size. In compact Rwanda the state is clearly functional as evidenced by its spotless countryside.
Small things can make a big difference. Rwanda has banned plastic bags, an unsightly feature of the landscape elsewhere in Africa.
If you arrive at the airport with a bottle of duty-free booze in a plastic bag, the bag will be taken from you.
What a difference it makes.
The drive from Congo to Kigali is achingly beautiful, twisting through cultivated hills dappled in stunning shades of green.
Kigali itself is also almost inhumanly clean. It is certainly the cleanest African city this correspondent has ever laid eyes on.
The Rwandan government has its critics to be sure, and its plastic-bag ban is no whitewash for other governance issues or its alleged interference in the affairs of its giant neighbour Congo.
But its war on garbage is surely a winner because it gets to the heart of an issue often explored in this blog - public health.
The fly-infested rubbish choking Goma's open sewers - a situation hardly unique to it in Africa - are breeding grounds for disease, pure and simple. Wider hygiene also suffers.
In Rwanda, this issue has been tackled head on. It all starts with a plastic bag.