1910 & 1920-S, Help Identifying Postmarks (13 Star Flag Etc)

Hi Everyone,
I have these old covers to auction but want to make sure I get a good description for them.

I have an old 1910 cover, and it has a flag on it as a postmark. I remember someone telling me a while back, something distinctive about it, but I could be wrong. Can anyone tell me about the flag postmark please?

Also I have a few covers from 1920's and I see the wavy lines have a number 11 and a number 19 in them, what does that represent?

Here are the photos. Thank you so much.
SueStamps

Sue, the South Bend flag cancels were both from an American Postal Supply model B14, the bottom on is a mute 3rd class.
The Chicago air mail is from a International model D32 and the rest are from Universal DT-300 series (most likely model DT302b4).
All are pretty common.

Edit: the numbers in the killer bars are the machine number, machine 11 and 19.

Thank you so much Russ.
WOW I am amazed at how much you know!
I am more fascinated than ever.
And I thought the numbers were for the date

Thank you very very much!
SueStamps

Here's another bit of information as to the full cover you scanned as addressed to T.J. Dale of Kenosha, Wisconsin.

At least we know he was a jeweler (watchmaker) and an optometrist (which accounts for the return address on your cover from an optical company).

As late as 1919, he was hiring for a watchmaker and optician at a wage of $35/week. Accounting for inflation, that's about $458/week in today's money.

How interesting!
I always wonder if there are ways to get a hold of people from the addresses on the old covers and contact them, tell them they can have it if they are interested. Where did you pull that information from?

Sometimes I get lucky and find the original letter inside, so much fun to read!

In the case of your cover dated to 1910, the personalities involved are long deceased, as they would have to be 120+ years old by now, so that's why it is relatively easy to find historical information on those old items. As for finding the above job listing, a Google search for "T.J. Dale" and "Kenosha" reveals several "hits" including the text of the Jewelers' Circular-Weekly. The above excerpt was simply taken from a several hundred page trade publication.

So I guess trying to find a child of, or grand children of the addresses would be hard. Thank you, hope your weekend is well.
SueStamps