Nostalgic/Erroneous Texas road map

[cjk374]

I was in a convenient store yesterday and found a Texas road map.  My girlfriend opened up the "mini-visor" version & something caught my eye:  I saw a US route shield on I-20 in west Texas.  I opened up the regular map & studied it closer.  This map company is The National Map Company (founded in 1983 & located in Tyler, TX!).  Their website:  www.nationalmapco.com   
Another error I found was in Odessa/Midland.  They have marked on the map an I-20E...I believe it could be BL I-20?  They did mark an I-20B between Pecos & Barstow, so they know the difference.  Why couldn't they mark old US 66?  That woulda been sweet.   

A side question:  Are these I-20 BLs all parts of the original US 80?  Did I-20 eat up all of the original US 80 west of Ft. Worth?

[NE2]

A side question:  Are these I-20 BLs all parts of the original US 80?  Did I-20 eat up all of the original US 80 west of Ft. Worth?

http://www.dot.state.tx.us/tpp/hwy/bi/bi0020b.htm
http://www.dot.state.tx.us/tpp/hwy/bi/bi0020e.htm
"Mileage transferred from US 80."

The letter appears in really small print on the signs. It's not useful for navigation.