The US was one of the few major military powers that went into World War II without a substantial infantry antitank weapon. Most countries had an antitank rifle of some sort, but the US just had some marginal antitank rifle grenades. That was rectified in late 1942 when the M1 Rocket Launcher – aka the Bazooka – was introduced. Using a 2.36” shaped charge warhead, it was able to penetrate about 4.7 inches of armor, which was effective through most of the war. A larger version went into development in 1943 though, because it was clear that the M1 would soon become obsolete.
The 3.5” M20 Super Bazooka was adopted in late 1945 and put into production in 1948, with it s first combat use coming in the Korean War. It was much more powerful, capable of penetrating 11 inches of armor plate. The launchers itself weighed just 13 pounds, with each rocket adding another 8.9 pounds. This, and the updated M20A1, would serve as the main US infantry antitank weapon until replaced by the 90mm recoilless rifle in the 1960s.