US 611 at US Ends.com

US 611 ALT in Philadelphia 1938 Esso

US 611 ALT on maps through at least 1950 1950 Official

US 611 ALT #2: In December 1952 (AASHO), US 611 was rerouted at Portland to a new toll bridge crossing into New Jersey. The old route became US 611 ALT.

US 611 avoids E Stroudsburg and Bangor 1940 Official

US 611 ALT through Portland and Delaware Water Gap 1956 Shell

In August 1962 (AASHO), US 611 was added to newly opened freeway around Stroudsburg west to a temporary connection to US 611 at today's Exit 303 on I-80. In October 1962 (AASHO), Pennsylvania revised their application to extend US 611 further along the new freeway to today's Exit 298 north of Tannersville. Pennsylvania wanted the old 611 to be an extension of US 611 ALT but in December 1962 AASHO declined and said US 611 Business should be considered instead.
In February 1963, Pennsylvania appealed the rejection of US 611 ALT extending through Stroudsburg. Notably, they said they were studying a new location south of Wind Gap plus today's PA 33 to relocate US 611 away from the Stroudsburg area entirely and both 611 and 611 ALT would disappear there. Pennsylvania supplied more information in April 1963, but was denied 611 ALT again in June 1963. But a Pocono Record photo shows they did post US 611 ALT. I have not found a map showing US 611 ALT through Stroudsburg.
In December 1964 (AASHO), US 611 was removed from New Jersey, replacing US 611 ALT between Portland and Stroudsburg. The old route became a bit of NJ 94, I-80 back into PA, and Foxtown Hill Rd. This is also when US 611 was removed from I-80 from Tannersville to Stroudsburg.

US 611 added to I-80 around western Stroudsburg 1964 Esso

US 611 ALT returns to being US 611 1966 Shell