The American Black Widow should have nothing upon its back but the black color it is. Specfically, the hour glass is on the belly of the spider.
The spider with a black line on its back is commonly known as the black widow spider.
black widow
Yes, the black spider with an orange dot on its back is likely a black widow spider, which is venomous.
A black widow spider is black with a red mark on it's abdomen; this might or might not be what you meant. The black widow sometimes has a red mark on her back, as well. The red backed spider of Australia, a relative of the black widow, has an orange red mark on the back.
black widow
Black widow
A black widow. This spider is only a black widow if the entire spider is black, with a round-ball looking back-body, female variety if there is a red hourglass shape marking on the underside of the spider. From the top black widows are completely black.
The black widow is the only spider in Georgia known to resemble a black widow but be entirely black. If you spot a black spider in Georgia that looks similar to a black widow but is completely black, it is likely a black widow spider. While rare, variations in color can occur within the species.
The black widow spider.
The hump on its back
The spider you are referring to is likely the black widow spider. The female black widow has a distinct red hourglass shape or white crescent on its abdomen. They are known for their venomous bite, so caution should be taken when encountering them.
The Black Widow spider's scientific name is Latrodectus Hesperus. That means western Black Widow spider.