All About Pocket Knives is a knife related resource center for buying, selling, researching, and discussing all things knives
http://www.allaboutpocketknives.com/knife_forum/
http://www.allaboutpocketknives.com/knife_forum/viewtopic.php?t=67539
Maybe the answer(s) you seek can be found here:LDF Knives wrote: ↑Sat Jul 25, 2020 3:43 pm I have a knife or two made by Boker and it's stamped USA on the Tang, when was this? and ended? Same quality as made in Germany? or Contracted?
Regarding quality, like most cutleries Böker had its ups and downs but Böker whether German or USA made has been consistently good. I’ve seen no significant quality differences between German and USA made Bökers. JMO. I have a soft spot for the USA Bökers - my dad was carrying one when we took him to the hospital before he passed.LDF Knives wrote: ↑Sat Jul 25, 2020 3:43 pm I have a knife or two made by Boker and it's stamped USA on the Tang, when was this? and ended? Same quality as made in Germany? or Contracted?
WOW!!RevolverGuy wrote: ↑Sat Jul 25, 2020 7:01 pm There is a lot of history on Boker. You could fill a book, and there are books out there covering this. I am copying and pasting from their website timeline page. It covers some of the more notable events in their history. https://www.bokerusa.com/timeline
1829: H. R. BOKER Cutlery formed in Remscheid Germany
1837: Herman migrated to US New York
1861:1866- Boker Germany produced muskets and 18,000 sabers for Union Army
1869: Heinr. Boker formed, operations moved to Solingen
1870: "Tree" logo registered on November 10
1870's to 1891- Boker was one of the top knife sellers in the US
1891: Tariff Act passed
1892: Valley Forge Cutlery established in Newark NJ
1899: Boker US merged with Valley Forge to produce product in US
1913: “Tree Brand" and “Arbolito" registered
1914:1918- all German knives were produced for the war effort
1914: Hermann BOKER Co filed for bankruptcy
1916: H BOKER Co purchases Cyclops Steel in Pennsylvania
1921: Maplewood NJ facility opened
1921- Boker Cutlery and Hardware consolidated with H BOKER & Co
1925: trademark 100 yr old chestnut tree struck by lightning
1928: 16 different knife pattern stainless steel blades manufactured in US
1930: Neutrality Act in limited trade with Germany
1941: Boker USA etch replaces German markings
1944: On Nov 5 British bombers dropped 783 tons of explosives on Solingen destroying the German facility
1947: Major John BOKER (US Army Intelligence) purchased the rights back from the US Government and renamed it “BOKER USA"
1950: Boker USA begins importing from Solingen again
1956: Boker purchases Schrade Knife Company to produce switchblades
1958: Switchblade Act adopted causing the closure of the Schrade plant that made these types of knives
1960: BUSA ends using bar shields and reintroduces round shields
1965: New Britain Machine Co purchases Boker USA which also owned Husky and Blackhawk brands
1968: New Britain absorbed into Litton Industries
1970: Boker USA acquired by J Wiss & Sons
1971: campaign of limited edition and commemorative series begins
1973: double shield / red shield series
1974:1978- Great American Story series introduced
1976: J Wiss purchased by Cooper Tools Group of North Carolina
1978: Boker US production moved to Statesboro GA
1983: US knife production ended
1984: United BOKER formed with Smoky Mountain Knife and Blue Ridge Knife to create a financial sales partnership
1986: Boker USA reformed and established sales offices and warehousing in Colorado
what a History!! Thanks! 
And that's just a part of it. Their history in Germany is just as complex and vast. The Boker family ventured all over and also have a rich history in both Argentina (Boker Arbolito) and Mexico (Casa Boker).