I tabulated data using the Census' ACS 2019 1-Year Estimates, grouping English, Scottish, Welsh, Scots-Irish, American, and British together (let's call it "British Isles Protestant," or BIP). The totals are for CSAs and are based on Reported Ancestry. Chicago really surprises me; I thought it would've been more in line with Detroit or so. I expected DC's BIP share to be much closer to Atlanta's.
On a separate note, what the heck happened to NYC's Irish population? It was around 2.7 million several years ago; now it's about 2.2 million. Boston's was 1.7, now 1.6.
Atlanta--Athens-Clarke County--Sandy Springs, GA-AL CSA
1,406,932 / 6,850,728
20.5% BIP
Seattle-Tacoma, WA CSA
925,539 / 4,903,675
18.9% BIP
Boston-Worcester-Providence, MA-RI-NH-CT CSA
1,478,958 / 8,287,710
17.8% BIP
Dallas-Fort Worth, TX-OK CSA
1,376,448 / 8,057,796
17.1% BIP
Detroit-Warren-Ann Arbor, MI CSA
865,150 / 5,341,994
16.2% BIP
Washington-Baltimore-Arlington, DC-MD-VA-WV-PA CSA
1,572,268 / 9,815,138
16% BIP
Phoenix-Mesa, AZ CSA
772,767 / 5,002,221
15.4% BIP
Philadelphia-Reading-Camden, PA-NJ-DE-MD CSA
959,071 / 7,209,620
13.3% BIP
Houston-The Woodlands, TX CSA
891,709 / 7,253,192
12.3% BIP
Miami-Port St. Lucie-Fort Lauderdale, FL CSA
779,035 / 6,889,936
11.3% BIP
San Jose-San Francisco-Oakland, CA CSA
1,059,604 / 9,665,887
11% BIP
Los Angeles-Long Beach, CA CSA
1,882,985 / 18,711,436
10.1% BIP
New York-Newark, NY-NJ-CT-PA CSA
2,088,701 / 22,589,036
9.2% BIP
Chicago-Naperville, IL-IN-WI CSA
883,891 / 9,824,302
9% BIP
Threaded Mode