normally, i just leave one line shitposts but since this is an actually interesting pod i've never seen properly developed I'll add some detailed thoughts of my own working from what i've read on here/SHWI before google removed access to it and my own thoughts. If someone wants to use this material for a map/scenario/TL feel free but just PM me so i can see it once it's done or if you'd like to ask for advice on it.
This is going to be well the sort of closest to OTL/focusing only on extrapolations take. Basically it assumes 1848-2018 follow a similar basic configuration to otl: two wars in europe started by Germany, Russia spending 60-90 years under some radical regime before collapsing and China facing severe troubles until mid-century before starting a period of rapid economic growth.
For starters, you 1) add more (dixie-focused) frontier areas with mexico's north/the far south 2) add a new "core" region into the US in the form of mexico's populated heartland. So you add a region that's 1) catholic 2) highly agrarian and unequeal but NOT a slave society 3) linguistically distinct. Basically you get a region that's willing to vote for states rights but NOT secede over slavery. To put the kind of changes we'd see from OTL in perspective: Decades of darkness saw the removal of one core region/'nation'/one of albions' seeds from the US, while taking half of another out. This TL adds an extra core region to the mix. The empty northern third or so historically speaking is just an extension of the US SW, with the populated core and to a lesser extent far south as the different areas. The old core? Some combo of quebec/dixie in terms of regional pride, linguistic difference* while the jungle south likely ends up a warmer, bilingual appalachia analogue.
Secondly, as far as timing of statehood goes? Likely an initial burst of slave states -- Sonora, Arizona, Rio Grande, Sinaloa, Yucatan with the rest waiting longer, but all in before 1900. The bits of central america that get grabbed before the end of slavery in hm, make it 1884 get in quickly. The rest, for speculative purposes make it panama/costa rica and El Salvador perhaps probably have to wait until the 1920s or 1930s. Philippines is grabbed during ttl's *spanish-american war in the 1850s probably during this world's era of decolonization, sometime 1940-70 with later dates as more realistic.
The first obvious effect this has is the ACW becomes first non-borderline inevitable, but increasingly unlikely as time progresses. Why? Slave states in northern mexico/bits of the far south/caribbean to counteract free states in the north and later on. The second factor is that with Mexico, and due to events mentioned below the caribbean are examples of societies where a rich minority manages to keep a lid on alot of the ah browner masses' discontent without slavery is an example to dixie. This helps cool southern tempers somewhat*, while on the northern side of things dividing various movements up -- expect anti-peonage movements, plus significantly earlier than OTL pro-integration/anti-segregation movements in the north popping up as butterflies.
The timing of abolition given the demographic effects of the POD, the example of the latin states/territories is sometime between 1880-95, with the exact date up to whoever does the scenario. Mexico as a source of cheap labor several decades earlier than OTL, combined with the US deciding to copy the Brits in the caribbean by bringing in asians from the US Philippines helps speed along abolition to get the dates mentioned rather than say 1920 since 1) you don't have to spend as much energy watching poorly paid free workers/contract labor as you do slaves 2) for whatever reasons whites tend to be less willing to segregate themselves from brown/asian people than blacks -- compare intermarriage rates between asians/hispanics and whites vs white/Black 3) The factors in 2) indicate it'd be doable to bring them on to the "white" sympathizing side of things to help vote to keep the system going. As far as the positive side of the ledger goes you have 1) much fewer dixie resentments for reactionaries to use 2) more secure non-black majorities in dixie to further weaken reactionaries 3) somewhat more northern pressure over time than OTL 1876-1954 4) More north/south connections leading to a *great migration starting 20 years earlier. However on the negative side of things you have: 1) instead of the KKK, the local sherriff's posse is enforcing white rule 2) an extra generation or so of bondage 3) later and more limited educational progress without the initial boost from OTL's freedmen's bureau*. Further complicating things are 1) the fact that people who are black but not coal-black have a way out in the form of passing for hispanic 2) Northern reformers being more gradualist/willing to do reform rather than OTL's two big reform boosts. The net effect is probably a similar timeframe for this world's version of *civil rights for blacks plus or minus 5-10 years of OTL, with parts of upper dixie desegregating in the 1950s along with more reform/moderating of the system than OTL's segregation saw.
Labor needs in both north and south would mean we get OTL's 1980s latin population explosion in the mainland US in the 1860s, combined with the same sort of migration from the Philippines later on. One big difference from OTL is the fact that the southern US gets this migration too. Take various side effects from
this old timeline, apply them to Mexicans/cubans/puerto ricans/dominicans move it a decade earlier than in the linked TL and say 20 years later for central americans/filipinos instead of blacks. This has big results both politically and culturally. Politically? See the next portion but as far as demographics goes, note the fact that even in 2018 OTL rates of racial intermarriage in the US tend to relate strongly to a particular state's asian/hispanic percentages. Culturally, it obviously leads to big changes for so many reasons. Food, accents, styles, popular music, etc.
As far as racial policy towards the residents of the new territories? Probably depending on state literacy/english fluency requirements to vote, with some more hardline areas having income requirements. These restrictions would be gone by 1940, even in Missisipi or South Carolina due to latins who moved north being an important voting block. Move it a decade later for those amerindians who still ID as indian or filipinos.
Overall, Racial attitudes end up diverging beyond just the delay of abolition. Latin Americans as part of the system means coalition-building is needed. The end result is a US that still has a Golden Age of Racism, but the firm one drop rule of OTL's north/after 1865 Dixie too isn't a thing. Instead of viewing say mixed race populations as degraded whites, the logic is that they're improved versions of the nonwhite portion. There's still extensive segregationism/discrimination both official, and after this world's version of the civil rights movement unofficial but the stark lines of OTL aren't quite there.
Religion in this TL's 19th century ends up more complicated thanks to adding a large catholic block combined with protestant responses to this. Protestant responses to it involve pushing for school prayer, pushing for civic symbolism to be Christian -- "In god we trust" on the currency early as one example. Missionary efforts in US bits of latin america, the Philippines act as distractions for protestant reform types in this TL. Efforts for prohibition, banning gambling, banning prostitution, women's suffrage and other issues all are delayed or weaker than OTL: Women's suffrage comes in the 1930s while prohibition never occurs nationally. Residual anti-catholicism in TTL leads to less protestant-catholic cooperation on film censorship in early years with weaker self-regulation than OTL. Pentecostalism may or may not happen in this TL. Catholicism in the US is both less irish-dominated, thus being less puritanical and less protestantized with heavy impacts on how catholic voters vote in TTL.
Non-slavery focused sectional issues see more compromising. Part of it is northern whigs/republicans/whatever party pops up to replace the GOP in the 1870s as abolitionist fever (temporarily) declines extracting concessions like the transcontinental railroad and OTL-style tariff raises/funding for infrastructure in return for the annexation of mexico/spanish american war/grabbing random bits of central America to go through. The result is that in ttl's say 1876 to use one date for comparison(end of reconstruction), you have a more activist federal government than OTL 1860 but less so than OTL 1876. The 20th century is another matter entirely.
The first obvious side effect of quieted sectional problems, at least between north/south is less barriers to expansion than OTL. Expect a Spanish-american war in the mid 1850s, with the US seizing cuba, PR and the Philippines with the last ending up a normal territory like the first two probably thanks to abolitionists trying to kill any expansion by sticking in a poison pill.* Walker's Nicaragua is another 1850s candidate along with likely both Hawaii and sometime 1858-68 the Dominican Republic. Problems with pirates means expect the sultanate of sulu to end up a territory sometime before 1880. Central America outside of Nicaragua? Annexed in bits and pieces 1860 to say 1894ish. With more precedent for it, this expansion likely continues into the 20th century -- when Britain offers to sell Canada the Bahamas in 190X and they're turned down there's a good chance of the US stepping up with an offer to buy it. Assuming similar 1910s, so chances are we'd write off some of the war debt to get Belize/Trinidad&Tobago in 1926. With this precedent we may even get Jamaica and/or guyana during the age of decolonization.
Liberia isn't annexed, but with continued abolitionist attention/focus for an extra generation is more clearly within the US sphere and stable. Say a per capita GDP/HDI comparable to OTL Barbados, a government that's CORRUPT but at least tries to be democratic and within the US tariff wall. More of a push for liberian settlement isn't demographically significant for the US but the kind of people who go there -- This TL's version of the civil rights movement will focus more on securing rights as Americans* and mostly lack Malcom X types.
Broadly speaking, many of the same 20th century political trends still happen extra core region on board aside. A *civil rights movement, probably down to having a preacher/ex-preacher as the main public face happens roughly on schedule even if things go smoother than OTL, more like Quebec's "quiet revolution". The welfare state gets expanded in mid-century, after a probable depression in the 20s or 30s, The US starts being more dominant overseas mid-century, all the stuff familiar to people who post those timelines with wikiboxes and photos of dead politicians on here. Race and the frontier still remain big reasons why full-on social democracy doesn't happen in the US. Despite that caveat, economic policy is more "left" in the sense of say having universal healthcare, stronger union rights* and a basic income*. The level of shifting would be comparable to say Canada/Australia/NZ in terms of leftward shifts over OTL. One big glaring omission from these TLs would be any analogue to the 1960s -- this is because of smoother progress for civil rights, no prohibition* leading to a less 'sober'/repressive mid-century culture to revolt against and a somewhat less puritanical overall US. At most the 1960s or 1970s see something comparable to the "flappers", with social changes happening in a more quiet or at least less public manner. One of the biggest changes would be a much more nationalistic, call it "America First" outlook than OTL due to a combination pro-assimilation/americanization propaganda being spread to the new territories, significantly less of a north/south rift without civil war-related divisions as the two big reasons*. Instead of our world's multiculturalism, you see something more like OTL's Brazil or Mexico which are very racially diverse but with an ideal common culture.
Inequality is most likelly within 2-3 points of OTL's US gini coefficient one way or another. Part of it is long distances making the Philippines lag in development, ending up somewhere between PR or MS depending on how the economics go to explain a good chunk of it. The old mexican core likely is as developed as Dixie OTL, Cuba as Florida 2.0 while the further caribbean/southern mexico/central america end up at lower dixie/appalachian levels of development.
Political parties in this set of ATLs could go many ways, for convenience's sake the most convergent realistic setup is going to be discussed. Basically, you have two parties of the right and left, but the constant presence of a Reform-level third party that depending on the timeframe/issue being discussed could either be more or less centrist than the big two. The party of the right is this tl's versions of the Democratic Party. Take the pre-1960s democratic coalition, add a large number of latin catholic conservatives and remove the left intellectuals from it to get the coalition. This isn't just OTL's GOP with a donkey as the logo, but somewhere between US-style conservatism and European/Latin American Christian Democracy*. The party on the other side, call it liberals/reform/progressive/whatever name you choose would end up being a liberal/social democratic coalition instead of OTL's Democratic Party that's a mashup of old-style rockefeller republicans, liberal/blue state business types and various ethnic/gender/sexual interest groups. The policies espoused would be a mix of traditional democratic party populism, social democracy but more in the UK old labor sense of applied christianity/focusing on working class issues. A quieter 1960s-70s, combined with a longer tradition of gradualism and compromise mean culture war divisions are less of a thing. Class is of course more of an open thing in politics dividing the two parties.*
immigration to this US after 192X would be much less than OTL and more european or (paler) Latin American than OTL. Besides more of a nationalist/xenophobic outlook in the electorate as a whole, there's also the fact that labor is stronger and an important part of one of the big 2's coalitions. The most likely policy turns probably involve reopening to Euro immigration in the 50s or 60s, but with only token african/asian immigration. Going by location alone: Venezuela, Colombia, Haiti as some of the most likely sources.
Bilingualism has been policy for a few generations, but the US is still supermajority anglophone. There are pockets of spanish-majority or near-majority speakers, but they are shrinking with those who don't know any english being in a few deeply isolated rural portions of southern Mexico/Central America. Accents and to a lesser extent vocabulary or slang are both quite spanish-influenced. The reduction of puritanical influences means that Americans would be more like australians/british in level of cursing/banter they're willing to do*.
Culture gets divergent quickly for SO MANY different reasons. Firstly, there's cultural/legal ramifications from having a less puritanical society on the content of literature/radio/TV/movies -- don't think OTL 2018 content in 1950, but lesser things like no married couples in seperate beds on TV in the 1950s. Cuisine gets divergent from OTL within 30 years of the POD thanks to the migrations north. Given that Mexican influences are being brought to Anglo-America before 1) The US being rich enough to have as cheap meat as we did in 1960 or now 2) frozen transportation, the resulting mix ends up quite divergent. More usage of chile peppers in food, along with rice & beans being even more common. Tex-mex cuisine, probably called something else would get big for OTL's reasons 20 years early. Filipino takeout would be everywhere. Football of both association football and *NFL, probably called "American Rules" football would be big. Baseball is likely on par with OTL, but with expanded teams*.
Geopolitics? Similar dynamics to OTL, even if national borders likely vary in the rvbomally/bruce munro's little pixel edits on maps. The only obvious changes are Latin America more tied in with the US, especially Haiti. Haiti would be even more of a puppet state, be as rich as OTL Saipan and probably HEAVILY resents the US being right next door to it. Latin America is much like OTL, except with more protestants*, even if still catholic majority/
From this stuff, plus whatever *didn't* get brought up shows that adding in Mexico to the US after 1848 adds Mothra-sized butterflies to US/world history even If you assume similar basic historical dynamics at play.
* An analogy would be how dixiecrats looked the other way in adding woman's rights to the CRA in hopes that it'd kill it.
* Besides South Carolina. Because it's South Carolina, they'lll threaten to secede every presidential eleciton until slavery is gone because that state was insane on the subject.
* Canada-style bilingualism laws by the 1930s or 1940s of course given one of the big two's base being old mexico.
* The pattern you likely see is an overall boost in education sometime in the 1850s say the south/mexico up to the standards of the mid-atlantic states. Given how lacking that is compared to New England's educational system the result isn't that great, obviously. As far as black education goes? Stagnates at the same literacy level of 1860 in dixie until 1884 when slow improvements begin while the north converges on par with OTL's rate. Think the "Talented Tenth" but moreso.
* A *great migration beginning in the late 1890s, combined with reducing the seperatist elements means more "colorblind" politics.
* US gets an urban working class comparable to OTL's 1900 in 1880, so more time for unions to build up before any red scare analogues come up.
* 70%+ supported it in the 1970s OTL, with OTL's cultural configuration. A US with an electorate less "small government"-minded probably gets it during the mid 20th century expansion of the welfare state.
* It came close to failing in OTL, with visibly WASPier demographics. A TL where anti-catholicism gets toned down earlier for just electoral strategy reasons? Never happens.
* Another reason is diversity being a thing generations early:
https://www.thenation.com/article/fear-of-diversity-made-people-more-likely-to-vote-trump/
* Less protestantized catholics, combined with more of a populist "conservative" tradition than OTL.
* The difference comes from, an electorate less WASP combined with cultural side effects of no ACW leading to US rich people feeling less of a need to seem middle class with resulting working/middle classes being less sympathetic to them. Think less liberal philantropist/folksy down home country multimillionaire but more european/latin american style willingness to be a playboy instead of "working" at a nominal job.
* And online trolling, if the reputation of Australians on anywhere that allows anonymous posting shows. With over 300-400 million people instead of Australia's 25 or so million...
* Stirling had the Mexico City aztecs as a team in the draka TL for either baseball or football.
* Missionaries learn Spanish to preach in Mexico end up applying those skills in Chile or Venezuela later on.