Figure 1.

Figure 2.

Figure 3.

Figure 4.

Figure A1.

Figure A2.

Table of group types and changes in standard distances_
| Group type | Modules | Avg. standard distance before; after (km) | Difference in standard distance (km) | Avg. years since inception |
|---|---|---|---|---|
| University | 36 | 2298; 3810 | 1512 | 8.5 |
| Professional | 21 | 2468; 3927 | 1460 | 6.6 |
| Secondary education | 20 | 527; 2441 | 1914 | 14.2 |
| Place-based cultural group | 16 | 1437; 2224 | 788 | 10.7 |
| Family | 15 | 1678; 2459 | 781 | 22.2 |
| Non-residential gathering | 14 | 2898; 4865 | 1967 | 6.5 |
| Non-place-based cultural group | 8 | 2463; 4267 | 1805 | 9.5 |
| Other | 3 | 4429; 5410 | 981 | 5.5 |
Top 20 most popular domestic alter cities and the number of egos with alters in these locations in the pre-period and post-period_
| Pre-city | Alters | Egos | Post-city | Alters | Egos |
|---|---|---|---|---|---|
| State College, PA | 1384 | 17 | State College, PA | 797 | 18 |
| Washington–Arlington–Alexandria, DC–VA–MD–WV | 803 | 12 | Washington–Arlington–Alexandria, DC–VA–MD–WV | 721 | 18 |
| Seattle–Tacoma–Bellevue, WA | 310 | 9 | New York–Northern New Jersey–Long Island, NY–NJ–PA | 346 | 17 |
| Poughkeepsie–Newburgh–Middletown, NY | 306 | 3 | Boston–Cambridge–Quincy, MA–NH | 276 | 17 |
| Chicago–Naperville–Joliet, IL–IN–WI | 288 | 10 | Charlotte–Gastonia–Concord, NC–SC | 239 | 8 |
| Boston–Cambridge–Quincy, MA–NH | 245 | 13 | Seattle–Tacoma–Bellevue, WA | 231 | 17 |
| Knoxville, TN | 222 | 5 | Chicago–Naperville–Joliet, IL–IN–WI | 224 | 16 |
| Cedar Rapids, IA | 205 | 2 | Philadelphia–Camden–Wilmington, PA–NJ–DE–MD | 207 | 15 |
| Charlotte–Gastonia–Concord, NC–SC | 199 | 4 | Atlanta–Sandy Springs–Marietta, GA | 193 | 12 |
| Atlanta–Sandy Springs–Marietta, GA | 196 | 7 | San Francisco–Oakland–Fremont, CA | 183 | 14 |
| San Francisco–Oakland–Fremont, CA | 186 | 8 | Los Angeles–Long Beach–Santa Ana, CA | 133 | 17 |
| Williamsport, PA | 180 | 3 | Dallas–Fort Worth–Arlington, TX | 132 | 15 |
| Austin–Round Rock, TX | 178 | 5 | Albany–Schenectady–Troy, NY | 129 | 6 |
| Philadelphia–Camden–Wilmington, PA–NJ–DE–MD | 173 | 9 | Knoxville, TN | 126 | 5 |
| Dallas–Fort Worth–Arlington, TX | 159 | 6 | Austin–Round Rock, TX | 120 | 15 |
| Appleton, WI | 125 | 2 | Williamsport, PA | 107 | 4 |
| Riverside–San Bernardino–Ontario, CA | 104 | 5 | Cedar Rapids, IA | 92 | 2 |
| New York–Northern New Jersey–Long Island, NY–NJ–PA | 63 | 16 | Pittsburgh, PA | 91 | 15 |
| Harrisburg–Carlisle, PA | 61 | 3 | Augusta–Richmond County, GA–SC | 82 | 5 |
| San Diego–Carlsbad–San Marcos, CA | 45 | 7 | Riverside–San Bernardino–Ontario, CA | 76 | 7 |
Summary statistics and geographic distribution of alters for each ego’s network_
| Network characteristics | Geographic characteristics | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Agent | Nodes | Edges | Average degree | Diameter | Density | Clustering coefficient | Modules; modularity | Average distance to friends (post-period) | Standard distance pre-period | Standard distance post-period | Change in standard distance | Change of mean center |
| A | 376 | 2679 | 12.3 | 10 | 0.038 | 0.36 | 4; 0.61 | 431 | 1468 | 2392 | 924 | 192 |
| B | 336 | 2533 | 14.5 | 9 | 0.045 | 0.53 | 13; 0.67 | 7827 | 5570 | 5691 | 121 | 667 |
| C | 601 | 7392 | 23.5 | 11 | 0.041 | 0.49 | 15; 0.62 | 277 | 1592 | 2395 | 803 | 383 |
| D | 370 | 3686 | 19.4 | 9 | 0.054 | 0.57 | 11; 0.71 | 2567 | 4377 | 3686 | -691 | 597 |
| E | 573 | 9833 | 33.8 | 10 | 0.06 | 0.47 | 12; 0.51 | 1409 | 2754 | 3727 | 973 | 1873 |
| F | 232 | 2706 | 22.3 | 5 | 0.10 | 0.53 | 12; 0.37 | 1174 | 2917 | 3903 | 986 | 455 |
| G | 361 | 2989 | 14.8 | 12 | 0.04 | 0.54 | 12; 0.71 | 215 | 887 | 2283 | 1396 | 368 |
| H | 437 | 6002 | 27.2 | 8 | 0.06 | 0.46 | 10; 0.51 | 1185 | 627 | 1267 | 640 | 188 |
| I | 403 | 5022 | 24.7 | 8 | 0.062 | 0.43 | 9; 0.52 | 687 | 3087 | 2383 | –704 | 518 |
| J | 437 | 2763 | 11.5 | 10 | 0.029 | 0.52 | 13; 0.78 | 1619 | 3726 | 4157 | 431 | 409 |
| K | 639 | 9784 | 30.5 | 7 | 0.048 | 0.33 | 10; 0.46 | 712 | 2534 | 2893 | 359 | 575 |
| L | 188 | 1002 | 10.4 | 10 | 0.057 | 0.64 | 6; 0.74 | 697 | 3047 | 2605 | –442 | 129 |
| M | 201 | 784 | 6.9 | 10 | 0.039 | 0.16 | 16; 0.46 | 8522 | 5727 | 5610 | –117 | 325 |
| N | 772 | 7143 | 18.2 | 11 | 0.024 | 0.44 | 16; 0.76 | 529 | 3274 | 3357 | 83 | 292 |
| O | 123 | 1028 | 15.8 | 9 | 0.137 | 0.74 | 9; 0.40 | 6701 | 3588 | 5564 | 1976 | 448 |
| P | 659 | 11,708 | 34.9 | 8 | 0.054 | 0.50 | 14; 0.52 | 1508 | 3726 | 3552 | –174 | 1150 |
| Q | 727 | 12,667 | 34.5 | 9 | 0.048 | 0.53 | 10; 0.69 | 492 | 1792 | 2951 | 1159 | 520 |
| R | 227 | 4412 | 37.7 | 6 | 0.172 | 0.55 | 10; 0.23 | 176 | 49 | 1658 | 1609 | 196 |
| S | 408 | 7639 | 37.0 | 7 | 0.092 | 0.52 | 9; 0.52 | 626 | 1693 | 2929 | 1236 | 441 |
| T | 566 | 4157 | 14.3 | 14 | 0.026 | 0.53 | 15; 0.75 | 1148 | 1156 | 2167 | 1011 | 560 |