that's a couched statement, considering no challenges have been made in the last two months. But you're being misleading.
FEDERAL: 1944, Public Health Service Act - allows the President via EO to enforce quarantines on a national level once a national public health emergency has been declared by the CDC, and if the CDC determines that states will not or cannot control infection within their own borders “necessary to prevent the introduction, transmission, or spread of communicable diseases from foreign countries into the States or possessions, or from one State or possession into another State or possession.” This includes Presidential authority for "the apprehension, detention, or conditional release of individuals . . . for the purpose of preventing” state to state transmission of a communicable disease. It also allows for travel permits.
(This is the 'absolute power' Trump spoke of and that the illiterate scoffed at)
(And this is why, my DH, carried a letter of authorization as a critical need worker that allowed him, specifically in Arkansas, to rent a hotel room when rules in Arkansas allowed only essential workers and the quarantined to rent hotel rooms in that state)
The Public Health Service Act of 1944 follows and enhances legislation passed by Congress in 1878, 1890, 1893, and 1906, all of which authorized measures to prevent international and inter-state transmission of epidemic and/or communicable disease considered a major health threat to the nation.
Violation of a federal quarantine carries a penalty of $100k or a year in jail, but if violation causes death, that penalty rockets to $250K plus extended jail time.
STATES: 1824 - Gibbons vs Ogden, SCOTUS - held that states held the power to quarantine. This ruling was reffirmed by SCOTUS in Compagnie Francaise de Navigation a Vapeur vs. Louisiana Board of Health, Argued October 29-30, 1900. Affirmed June 2, 1902. 186 U.S. 380.
Each state, under their individual duty to protect the health, welfare and safety of its citizens via police powers held by each state, has enacted legislation that allows for the Governor, on recommendation of county health officials, or for county health officials themselves, to quarantine individuals or areas to control infectious disease within the boundries of their states, including closing borders. Whether it be forced quarantine of individuals, such as tuberculosis and measles patients under treatment, or isolating of entire neighborhoods or townships. (current example: Gallup, NM)
Quarantines have been practiced throughout history. And as your post amply shows, it’s been both practiced and held constitutional throughout this nation’s history. All this nonsense about requiring masks, social distancing or enforcing quarantines being ‘unconstitutional’ is a recent invention of the last few weeks.
Wall Street and the big money interests are losing money with these anti-Wuhan plague measures, so they’ve ginned up talk radio and the right-wing blogosphere to push this new ‘constitutional right’ that they’ve pulled out of their butt.
Along with the billionaires, the chi-com trolls are riling up the crazies on both the left and right with conspiracies blaming everyone except for the true culprit— the chi-com dictatorship.
This is in addition to your points.
Basically state governors have a lot of room in dealing with epidemics through their own orders, but there are also a lot of ways they and their underlings can exceed that emergency authority. Many governors are doing both, which makes things confusing. And makes flat statements like mine pretty silly.
Lookner has stories about stompy feets being arrested across Texas. That hair cutter got a week in jail and a $7,000 fine.