Were the traffic light and gas mask invented by an African-American? Or not?

A quick search on the internet for the inventor of the traffic light uncovers numerous references to an African-American inventor named Garrett A. Morgan, who made some kind of traffic signal in 1923. But when I try to ascertain the significance of his invention, I find all sorts of different claims. According to some internet sources, Morgan invented the first traffic light; according to others, he invented the first traffic signal but not necessarily the first traffic light; others say he invented the first automatic traffic signal but not necessarily the first traffic signal; others say “first traffic signal to receive a patent” , and so forth. To make matters worse, when I examined the issue in more depth at the local university library, I found a few sources that appear to contradict all of these claims. For instance the book Traffic Devices: Historical Aspects Thereof, by Gordon Sessions, documents the following steps in the development of the modern traffic light:
[ul][li]The first manually-operated traffic signal using colored gas lamps and semaphores was installed in London in 1868.[/li][li]Ernest E. Sirene invented the first electrically operated semaphore-type traffic signal (patent granted 1910).[/li][li]A Salt Lake City policeman named Lester Wire may have invented the first electric traffic light in 1912 (since the year is hard to verify, this claim is uncertain).[/li][li]James Hoge invented an electric automatic traffic light in 1913; this was manufactured by the American Traffic Signal Company and was installed in Cleveland at the corner of 105th and Euclid Ave. in 1914 (though Hoge’s patent was not granted until 1918).[/li][li]A Detroit Police officer named William Potts invented the first four-way, red-amber-green traffic light in 1920.[/li][/ul]All of the above apparently predated Morgan’s signal, which was patented in 1923 and used semaphore-like flags to direct traffic. So where does Morgan’s fit in? What is its significance? It must be the first something, but I can’t seem to find any agreement on what that something is.

In a similar vein, popular lore celebrates the same Garrett Morgan as the inventor of the gas mask (actually a “smoke hood” in 1914). See for example:

http://inventors.about.com/science/inventors/cs/blackinventors/index_2.htm

http://www.grc.nasa.gov/WWW/PAO/pressrel/99_16.htm

However, a perusal through Bruce Held’s History of Respiratory Devices in the U.S. (1970) turns up many similar devices that performed essentially the same function – preventing smoke and dust inhalation – as Morgan’s device, and were invented earlier. In the U.S. alone, there was the Nealy Smoke Mask (1877), Bernard Loeb’s respirator (1875), Merriman’s Smoke Mask (1892), Vajen-Bader’s Smoke Protector (1896), the Muntz Respirator (1902), etc., etc., etc. But when I search on the internet for the inventor of the gas mask the answer is invariably Morgan. Why?

The about.com page links to a mirror site which explains why the signal was important:

Previous signals only had a go and stop position. His signal became the standard until the yellow light was adopted.

His invention signalled for all directions to stop before giving a go, and could placed in a yield position when not in service (such as in the middle of the night.)

Thanks for the link. The following sentence from that site seems to clarify things:

“While other inventors are reported to have experimented and even marketed their own three-position traffic signals, Garrett A. Morgan was the first to apply for and acquire a U.S. patent for such a device.”

I had been confused because William Potts apparently designed his red-yellow-green traffic light before Morgan came up with his own design. But it seems that Potts never sought a patent for his light, so Morgan’s T-pole unit was apparently the first patented 3-signal device.